Statement of Comprehensive Income [Abstract] Revenues Revenues Cost of revenues Cost of Revenue Selling, general and administrative expenses Selling, General and Administrative Expense Acquisition and integration costs (Note 4) Business Combination Acquisition And Integration Related Costs This element represents acquisition-related and integration related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; including costs of registering and issuing debt and equity securities; business integration costs, systems integration and conversion costs, and severance and other employee-related costs. Operating income Operating Income (Loss) Interest expense Interest Expense Other (income) expense, net Other Nonoperating Income (Expense) Income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Provision for income taxes (Note 6) Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Other comprehensive income, net of tax (Note 9) Other Comprehensive Income (Loss), Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Earnings per share (Note 2): Earnings Per Share [Abstract] Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Cash dividends declared per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Cash dividends paid per share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Equity [Abstract] Changes in Accumulated Other Comprehensive Income Attributable to the Company's Fixed Interest Rate Swap Cash Flow Hedges Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block] Commitments and Contingencies Disclosure [Abstract] Commitments And Contingencies [Table] Commitments And Contingencies [Table] Commitments and contingencies. Purchase Commitment, Excluding Long-term Commitment [Axis] Purchase Commitment, Excluding Long-term Commitment [Axis] Purchase Commitment, Excluding Long-term Commitment [Domain] Purchase Commitment, Excluding Long-term Commitment [Domain] AAV Purchase Commitment AAV Purchase Commitment [Member] AAV Purchase Commitment [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Scitor Holdings, Inc. Scitor Holdings Inc [Member] Scitor Holdings Inc. Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Former Parent Former Parent [Member] Former parent. Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Government Investigations And Reviews Government Investigations And Reviews [Member] Government investigations and reviews. Letters of Credit Financial Standby Letter of Credit [Member] Surety Bonds Surety Bond [Member] Commitments And Contingencies [Line Items] Commitments And Contingencies [Line Items] Commitments and contingencies. Purchase consideration paid, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Amount deposited to adjustment and indemnification escrow accounts included in cash consideration paid Business Combination Amount Deposited To Adjustment And Indemnification Escrow Accounts Included In Cash Consideration Paid Business combination amount deposited to adjustment and indemnification escrow accounts included in cash consideration paid. Amount released from escrow account Business Combination Amount Deposited To Adjustment And Indemnification Escrow Accounts Amounts Released Business combination amount deposited to adjustment and indemnification escrow accounts amounts released. Distribution from escrow for settlement of a claim recognized as a reduction to selling, general, and administrative costs Business Combination, Escrow Deposit Disbursements Received Business Combination, Escrow Deposit Disbursements Received Escrow balance Escrow Deposit Contingent losses, threshold for loss sharing with former parent Loss Contingency Threshold For Loss Sharing Loss contingency threshold for loss sharing with former Parent. Contingent losses, loss sharing percentage in excess of threshold Loss Contingency Loss Sharing Percentage In Excess Of Threshold Loss contingency loss sharing percentage in excess of threshold. Estimated net amounts to be refunded for potential adjustments Loss Contingency Accrual Outstanding obligations Guarantor Obligations, Current Carrying Value Inventories, prepaid expenses and other current assets Inventory, Prepaid Expenses, And Other Current Assets Inventory, Prepaid Expenses, And Other Current Assets Revenue from Contract with Customer [Abstract] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Contract retentions Contract Retentions [Member] Contract Retentions [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Receivables, net Trade Accounts Receivable [Member] Accounts payable and accrued liabilities Accounts Payable and Accrued Liabilities [Member] Other long-term liabilities Other Noncurrent Liabilities [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Billed and billable receivables, net Billed Contracts Receivable Contract assets Contract with Customer, Asset, Net Contract liabilities - current Contract with Customer, Liability, Current Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable Contract liabilities - non-current Contract with Customer, Liability, Noncurrent Revenues Revenue from Contract with Customer [Text Block] Debt Disclosure [Abstract] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Term Loan A Facility due August 2021 Term Loan A Facility Due August Two Thousand Twenty One [Member] Term loan A facility due august two thousand twenty one. Term Loan B Facility Due October Two Thousand Twenty Five Term Loan B Facility Due October Two Thousand Twenty Five [Member] Term Loan B Facility Due October Two Thousand Twenty Five [Member] Term Loan B Facility due May 2022 Term Loan B Facility Due May Two Thousand Twenty Two [Member] Term loan b facility due may two thousand twenty two. Debt Instrument [Line Items] Debt Instrument [Line Items] Stated interest rate Debt Instrument, Interest Rate, Stated Percentage Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Principal amount of long-term debt Long-term Debt, Gross Unamortized debt issuance costs, total long-term debt Debt Issuance Costs, Net Total long-term debt Long-term Debt Less current portion Long-term Debt, Current Maturities Principal amount of long-term debt, net of current portion Debt Instrument Non Current Carrying Amount Debt instrument non current carrying amount. Unamortized debt issuance costs, total long-term debt, net of current portion Debt Issuance Costs, Noncurrent, Net Total long-term debt, net of current portion Long-term Debt, Excluding Current Maturities Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Earnings Per Share [Table] Earnings Per Share [Table] Earnings per share. Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Stock Options Employee Stock Option [Member] Computation Of Earnings Per Share [Line Items] Computation Of Earnings Per Share [Line Items] Computation of earnings per share. Basic weighted-average number of shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive common share equivalents - stock options and other stock-based awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted weighted-average number of shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Diluted Antidilutive stock options excluded (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Customer [Axis] Customer [Axis] Customer [Domain] Customer [Domain] Department of Defense Department Of Defense [Member] Department Of Defense [Member] Other federal government agencies Other Federal Government Agencies [Member] Other Federal Government Agencies [Member] Commercial, state and local Commercial, State, And Local Agencies [Member] Commercial, State, And Local [Member] Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Axis] Contract with Customer, Basis of Pricing [Domain] Contract with Customer, Basis of Pricing [Domain] Cost reimbursement Cost Reimbursement Contract [Member] Cost Reimbursement Contract [Member] Time and materials (T&M) Time-and-materials Contract [Member] Firm-fixed price (FFP) Fixed-price Contract [Member] Contractor [Axis] Contractor [Axis] Contractor [Axis] Contractor [Domain] Contractor [Domain] [Domain] for Contractor [Axis] Prime contractor to federal government Prime Contractor [Member] Prime Contractor [Member] Subcontractor to federal government Subcontractor [Member] Subcontractor [Member] Other Other Contractor [Member] Other Contractor [Member] Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative [Table] Derivative [Table] Hedging Relationship [Axis] Hedging Relationship [Axis] Hedging Relationship [Domain] Hedging Relationship [Domain] Cash Flow Hedging Cash Flow Hedging [Member] Term loan interest rate swaps 1 Term loan interest rate swaps 1 [Member] Term loan interest rate swaps 1 Term loan interest rate swaps 2(2) Term loan interest rate swaps 2 [Member] Term loan interest rate swaps 2 Term loan interest rate swaps 3(4) Term loan interest rate swaps 3 [Member] Term loan interest rate swaps 3 Term loan interest rate swaps 4(5) Term loan interest rate swaps 4 [Member] Term loan interest rate swaps 4 Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest Rate Swaps Interest Rate Swap [Member] Derivative [Line Items] Derivative [Line Items] Derivative, Cash Received on Hedge Derivative, Cash Received on Hedge Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Before Tax1 Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Before Tax1 Accumulated other comprehensive income loss cumulative changes in net gain loss from cash flow hedges effect before tax 1. Notional amount Derivative, Notional Amount Pay fixed rate Derivative, Fixed Interest Rate Receive variable rate Debt Instrument, Description of Variable Rate Basis Settlement and termination Derivative Contract Settlement And Termination Derivative contract settlement and termination. Asset Fair Value Derivative Assets (Liabilities), at Fair Value, Net Derivative instrument floor rate Derivative, Floor Interest Rate Accounting Policies [Abstract] Reconciliation of Cash, Cash Equivalents and Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Schedule of Cumulative Effect of Adopting ASC 606 Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Legal Proceedings and Other Commitments and Contingencies Legal Matters and Contingencies [Text Block] Amortization Period [Axis] Amortization Period [Axis] Amortization Period [Axis] Amortization Period [Domain] Amortization Period [Domain] [Domain] for Amortization Period [Axis] Quarterly Periods Beginning January 31, 2020 [Member] Quarterly Periods Beginning January 31, 2020 [Member] Quarterly Periods Beginning January 31, 2020 [Member] Quarterly Periods Beginning January 31, 2021 [Member] Quarterly Periods Beginning January 31, 2021 [Member] Quarterly Periods Beginning January 31, 2021 [Member] Quarterly Periods Beginning January 31, 2022 [Member] Quarterly Periods Beginning January 31, 2022 [Member] Quarterly Periods Beginning January 31, 2022 [Member] Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] Eurodollar Eurodollar [Member] Base Rate Base Rate [Member] London Interbank Offered Rate (LIBOR) [Member] London Interbank Offered Rate (LIBOR) [Member] Term Loan A Facility Commitment Due October Two Thousand Twenty Three Term Loan A Facility Commitment Due October Two Thousand Twenty Three [Member] Term Loan A Facility Commitment Due October Two Thousand Twenty Three Revolving Credit Facility Revolving Credit Facility [Member] Credit Facility [Axis] Credit Facility [Axis] Credit Facility [Domain] Credit Facility [Domain] Second Amended and Restated Credit Agreement Second Amended And Restated Credit Agreement [Member] Second amended and restated credit agreement. Third Amended Credit Agreement Third Amended Credit Agreement [Member] Third Amended Credit Agreement [Member] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Maximum Maximum [Member] Debt Covenant Period [Axis] Debt Covenant Period [Axis] Debt Covenant Period [Axis] Debt Covenant Period [Domain] Debt Covenant Period [Domain] [Domain] for Debt Covenant Period First Term [Member] First Term [Member] First term. Second Term [Member] Second Term [Member] Second term. Third Term [Member] Third Term [Member] Third term. Fourth Term [Member] Fourth Term [Member] Fourth Term [Member] Credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Line Of Credit Facility, Merger Feature, Increase Borrowing Capacity Line Of Credit Facility, Merger Feature, Increase Borrowing Capacity Line Of Credit Facility, Merger Feature, Increase Borrowing Capacity Principal amount of long-term debt Long Term Debt, Gross, Merger Termination Feature Long Term Debt, Gross, Merger Termination Feature Long Term Debt, Gross, Merger Termination Feature Gain (Loss) on Extinguishment of Debt Gain (Loss) on Extinguishment of Debt Revolving credit facility, current Long-term Line of Credit Debt instrument, reduction to interest rate margin Debt Instrument, Reduction To Interest Rate Margin Debt Instrument, Reduction To Interest Rate Margin Interest rate margin under credit agreement Debt Instrument, Basis Spread on Variable Rate Line of Credit Facility, Commitment Fee Percentage Line of Credit Facility, Commitment Fee Percentage Debt Instrument Amortization Of Principal and Accrued Interest, Percentage Debt Instrument Amortization Of Principal And Accrued Interest, Percentage Debt Instrument Amortization Of Principal And Accrued Interest, Percentage Debt instrument floor rate Debt Instrument Floor Rate Debt instrument floor rate. Debt instrument, financing fee Payments of Financing Costs Debt issuance costs Payments of Debt Issuance Costs Credit Agreement financial covenant, leverage ratio Ratio Of Indebtedness To Earnings Before Interest Taxes Depreciation And Amortization Ratio of indebtedness to earnings before interest taxes depreciation and amortization. Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Net income Adjustments to reconcile net income to net cash provided by operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Stock-based compensation expense Share-based Compensation Loss on extinguishment of debt Provision for inventory Inventory, Firm Purchase Commitment, Loss Increase (decrease) resulting from changes in operating assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Receivables Increase (Decrease) in Accounts Receivable Inventory, prepaid expenses and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other assets Increase (Decrease) in Other Noncurrent Assets Accounts payable and accrued liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Accrued payroll and employee benefits Increase (Decrease) in Employee Related Liabilities Other long-term liabilities Increase (Decrease) in Other Noncurrent Liabilities Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities, Continuing Operations Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Expenditures for property, plant, and equipment Payments to Acquire Property, Plant, and Equipment Other Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities, Continuing Operations Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Dividend payments to stockholders Payments of Ordinary Dividends, Common Stock Principal payments on borrowings Repayments of Debt Issuances of stock Proceeds from Issuance of Common Stock Stock repurchased and retired or withheld for taxes on equity awards Payments for Repurchase of Common Stock Disbursements for obligations assumed from Scitor acquisition Disbursements For Obligations Assumed From Acquisition Disbursements for obligations assumed from acquisition. Proceeds from borrowings Proceeds from Issuance of Debt Debt issuance costs Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net increase (decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period (Note 1) Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Revenue, Initial Application Period Cumulative Effect Transition [Table] Revenue, Initial Application Period Cumulative Effect Transition [Table] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Axis] Initial Application Period Cumulative Effect Transition [Domain] Initial Application Period Cumulative Effect Transition [Domain] Calculated under Revenue Guidance in Effect before Topic 606 Calculated under Revenue Guidance in Effect before Topic 606 [Member] Difference between Revenue Guidance in Effect before and after Topic 606 Difference between Revenue Guidance in Effect before and after Topic 606 [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2014-09 Accounting Standards Update 2014-09 [Member] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Revenue, Initial Application Period Cumulative Effect Transition [Line Items] Operating income Receivables, net Accounts Receivable, Net, Current Other assets Other Assets, Noncurrent Accounts payable and accrued liabilities Accounts Payable and Other Accrued Liabilities, Current Retained earnings Retained Earnings (Accumulated Deficit) Earnings Per Share Earnings Per Share [Text Block] Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Total current assets Assets, Current Goodwill Goodwill Intangible assets (net of accumulated amortization of $70 million and $55 million at November 2, 2018 and February 2, 2018, respectively) Finite-Lived Intangible Assets, Net Property, plant, and equipment (net of accumulated depreciation of $156 million and $143 million at November 2, 2018 and February 2, 2018, respectively) Property, Plant and Equipment, Net Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Accrued payroll and employee benefits Employee-related Liabilities, Current Long-term debt, current portion (Note 7) Total current liabilities Liabilities, Current Long-term debt, net of current portion (Note 7) Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Commitments and contingencies (Note 10) Commitments and Contingencies Equity: Stockholders' Equity Attributable to Parent [Abstract] Common stock, $.0001 par value, 1 billion shares authorized, 43 million shares issued and outstanding as of November 2, 2018 and February 2, 2018 Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital, Common Stock Accumulated other comprehensive income (Note 9) Accumulated Other Comprehensive Income (Loss), Net of Tax Total equity Stockholders' Equity Attributable to Parent Total liabilities and equity Liabilities and Equity Capitalized Contract Cost [Table] Capitalized Contract Cost [Table] Inventory, prepaid expenses and other current assets Inventory, Prepaid Expenses, And Other Current Assets [Member] Inventory, Prepaid Expenses, And Other Current Assets [Member] Other assets Other Assets [Member] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Axis] Capitalized Contract Cost [Domain] Capitalized Contract Cost [Domain] Pre-contract costs Pre-Contract Cost [Member] Pre-Contract Cost [Member] Fulfillment costs - current Fulfillment Cost, Current [Member] Fulfillment Cost, Current [Member] Fulfillment costs - non-current Fulfillment Cost, Non-Current [Member] Fulfillment Cost, Non-Current [Member] Capitalized Contract Cost [Line Items] Capitalized Contract Cost [Line Items] Capitalized Contract Cost, Amortization Capitalized Contract Cost, Amortization Deferred costs Capitalized Contract Cost, Net Pending Acquisition of Engility [Abstract] Pending Acquisition of Engility [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Employee Stock Option Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Performance Shares Performance Shares [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Options granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures Stock option weighted-average exercise price (in dollars per share) Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted-average grant date fair value of options awarded (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Contractual term Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period Vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Awards granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Weighted-average grant date fair value (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share awards granted (in shares) Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Contingently Issuable Shares Share-based compensation arrangement by share-based payment award, equity instruments other than options, contingently issuable shares. Percentage of target shares Maximum Range Of Awards Of Target Number Of Shares The maximum percentage of target number of shares to be issued. Segment Reporting Segment Reporting, Policy [Policy Text Block] Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Restructuring Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block] Reporting Periods Fiscal Period, Policy [Policy Text Block] Operating Cycle Construction Contractors, Operating Cycle, Policy [Policy Text Block] Derivative Instruments Designated as Cash Flow Hedges Derivatives, Policy [Policy Text Block] Accounting Standards Updates New Accounting Pronouncements, Policy [Policy Text Block] Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Revenue Recognition, Change in Estimates, Disaggregation of Revenues, Contract Balances, Deferred Costs Revenue from Contract with Customer [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Inventory Inventory, Policy [Policy Text Block] Schedule of Derivative Instruments Schedule of Derivative Instruments [Table Text Block] Schedule of Restructuring and Related Costs [Table] Schedule of Restructuring and Related Costs [Table] Engility Holdings, Inc. Merger Engility Holdings, Inc. Merger [Member] Engility Holdings, Inc. Merger [Member] Engility Holdings, Inc. Merger Engility Holdings, Inc. Merger [Line Items] Engility Holdings, Inc. Merger [Line Items] Common shares conversion ratio Business Combination, Equity Right Conversion, Common Shares Conversion Ratio Business Combination, Equity Right Conversion, Common Shares Conversion Ratio Long-term Debt, Gross Business Combination, Estimated Acquisition Value Business Combination, Estimated Acquisition Value Business Combination, Estimated Acquisition Value Business Acquisition, Share Price Business Acquisition, Share Price acquisition costs incurred acquisition costs incurred acquisition costs incurred Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction Debt Issuance Costs Incurred During Noncash or Partial Noncash Transaction Stock Issue Costs Stock Issue Costs Stock Issue Costs capitalized during the period. Business Combination, Acquisition Related Costs Business Combination, Acquisition Related Costs Business Combination, Integration Related Costs Business Combination, Integration Related Costs Ineffective portion of the unrealized change in fair value, net of tax Derivative, Net Hedge Ineffectiveness Gain (Loss) Unrealized gains estimated to be reclassified from accumulated other comprehensive income into earnings in the next twelve months Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Pending Acquisition of Engility saic_PendingAcquisitionofEngility [Text Block] Pending Acquisition of Engility Business Overview and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, remaining performance obligation (percent) Revenue, Remaining Performance Obligation, Percentage Revenue, remaining performance obligation, period Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Debt Obligations Debt Disclosure [Text Block] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Change in Accounting Estimate by Type [Axis] Change in Accounting Estimate by Type [Axis] Change in Accounting Estimate, Type [Domain] Change in Accounting Estimate, Type [Domain] Change in Accounting Method Accounted for as Change in Estimate Change in Accounting Method Accounted for as Change in Estimate [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Increase (decrease) in income from change in contract estimates Increase (decrease) in income from change in contract estimates per diluted share (in dollars per share) Contract with customer, performance obligation satisfied in previous period Contract with Customer, Performance Obligation Satisfied in Previous Period Contract with customer, liability, revenue recognized Contract with Customer, Liability, Revenue Recognized Remaining performance obligation Revenue, Remaining Performance Obligation, Amount Assets Liabilities and Equity Retained earnings Restricted cash included in other assets Restricted Cash and Cash Equivalents, Noncurrent Cash, cash equivalents and restricted cash Intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Property, plant and equipment, accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Equity Components Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Shares of common stock Common Stock [Member] Additional paid-in capital Additional Paid-in Capital [Member] Retained earnings Retained Earnings [Member] Accumulated other comprehensive income AOCI Attributable to Parent [Member] Statement [Line Items] Statement [Line Items] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, beginning (in shares) Balance, beginning Cumulative impact from adopting ASC 606 (Note 1) on February 3, 2018 Cumulative Effect of New Accounting Principle in Period of Adoption Issuances of stock (in shares) Stock Issued During Period, Shares, New Issues Issuances of stock Stock Issued During Period, Value, New Issues Other comprehensive income, net of tax Cash dividends of $0.93 per share Dividends, Common Stock, Cash Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Repurchases of stock (in shares) Stock Repurchased and Retired During Period, Shares Repurchases of stock Stock Repurchased and Retired During Period, Value Balance, ending (in shares) Balance, ending Reconciliation of Weighted Average Number of Shares Outstanding Used to Compute Basic and Diluted EPS Schedule of Weighted Average Number of Shares [Table Text Block] Stock-Based Awards Excluded from Weighted Average Number of Shares Outstanding Used to Compute Diluted EPS Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Accounting Standards Update 2014-09, Revenue Recognition, Adjusted Cost-To-Cost Basis Accounting Standards Update 2014-09, Revenue Recognition, Adjusted Cost-To-Cost Basis [Member] Accounting Standards Update 2014-09, Revenue Recognition, Adjusted Cost-To-Cost Basis [Member] Restructuring Type [Axis] Restructuring Type [Axis] Type of Restructuring [Domain] Type of Restructuring [Domain] Employee Severance Employee Severance [Member] Contract Termination Contract Termination [Member] Number of operating segments Number of Operating Segments Number of market service line organizations Number Of Market Service Line Organizations Number Of Market Service Line Organizations Number of reportable segments Number of Reportable Segments Restructuring costs Restructuring and Related Cost, Cost Incurred to Date Restructuring costs, employee severance Restructuring Charges Restructuring costs, cash payments Payments for Restructuring Restructuring costs, settlement period Restructuring And Related Cost, Settlement Period Restructuring And Related Cost, Settlement Period Operating cycle (greater than) Contract Operating Cycle Contract Operating Cycle Reduction in inventories, prepaid expenses and other current assets Reduction in accounts payable and accrued liabilities Long-term Debt Schedule of Long-term Debt Instruments [Table Text Block] Changes in Accumulated Other Comprehensive Income by Component Comprehensive Income (Loss) Note [Text Block] Unrealized gains (losses) on fixed interest rate swap cash flow hedges, beginning balance, pre-tax amount Unrealized gains (losses) on fixed interest rate swap cash flow hedges, other comprehensive income (loss) before reclassifications, pre-tax amount Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, amounts reclassified from accumulated other comprehensive income, pre-tax amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, net other comprehensive income (loss), pre-tax amount Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, ending balance, pre-tax amount Unrealized gains (losses) on fixed interest rate swap cash flow hedges, beginning balance, income tax Accumulated Other Comprehensive Income Loss Cumulative Changes In Net Gain Loss From Cash Flow Hedges Effect Tax The tax effect from accumulated change, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's increase (decrease) in deferred hedging gains or losses. Unrealized gains (losses) on fixed interest rate swap cash flow hedges, other comprehensive income (loss) before reclassifications, income tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, amounts reclassified from accumulated other comprehensive income, income tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, net other comprehensive income (loss), income tax Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, ending balance, income tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, beginning balance, net amount Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, other comprehensive income (loss) before reclassifications, net amount Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, amounts reclassified from accumulated other comprehensive income, net amount Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, net other comprehensive income (loss), net amount Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Unrealized gains (losses) on fixed interest rate swap cash flow hedges, ending balance, net amount Cash dividends paid per share (in dollars per share) Derivative Instruments Designated as Cash Flow Hedges Derivative Instruments and Hedging Activities Disclosure [Text Block] Income Taxes [Table] Income Taxes [Table] Income taxes. Income Taxes [Line Items] Income Taxes [Line Items] Income taxes. Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Liabilities for uncertainty in income taxes Liability for Uncertainty in Income Taxes, Noncurrent Unrecognized tax benefits Unrecognized Tax Benefits Disaggregated Revenues Disaggregation of Revenue [Table Text Block] Contract Related Assets and Liabilities Contract with Customer, Asset and Liability [Table Text Block] Deferred Costs Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] Document And Entity Information [Abstract] Document and entity information. Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Trading Symbol Trading Symbol Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Emerging Growth Company Entity Emerging Growth Company Entity Small Business Entity Small Business