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[Member] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Number of directors appointable by Company Number of Directors Appointable Number of Directors Appointable Number of directors Number of Directors Number of Directors Due to affiliate, current Due to Affiliate, Current Payments to related party Related Party Transaction, Amounts of Transaction Receivables [Abstract] Accounts Receivable, Net of Allowance Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Payables and Accruals [Abstract] Vendor payables Accounts Payable, Trade, Current Accrued expenses Accrued Liabilities, Current Total accounts payable and other accrued expenses Interest expense on debt Interest Expense, Debt Deferred Payment Obligation Interest Deferred Payment Obligation, Interest Payment Deferred Payment Obligation, Interest Payment Amortization of Debt Issuance Cost (DIC) and Original Issue Discount (OID) Amortization of Debt Issuance Costs and Discounts Other Interest Income (Expense), Other Interest Income (Expense), Other Total Interest Expense Interest Expense Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Post-retirement Plans Accumulated 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Activities Cash flows from financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from issuance of common stock Proceeds from Issuance of Common Stock Stock option exercises Proceeds from Stock Options Exercised Repurchases of common stock Payments for Repurchase of Common Stock Cash dividends paid Payments of Dividends Dividend equivalents paid to option holders Payments of Capital Distribution Repayment of debt Repayments of Debt Proceeds from debt issuance Proceeds from Issuance of Long-term Debt Payment on contingent liabilities from acquisition Payment for Contingent Consideration Liability, Financing Activities Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities Net (decrease) increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents––beginning of period Cash and cash equivalents––end of period Supplemental disclosures of cash flow information Supplemental Cash Flow Information [Abstract] Cash paid during the period for: Cash Payments Abstract Cash paid during the period for: Interest Interest Paid, Excluding Capitalized Interest, Operating Activities Income taxes Income Taxes Paid, Net Supplemental disclosures of non-cash investing and financing activities Noncash Investing and Financing Items [Abstract] Noncash financing activities Noncash Financing Activities Noncash Financing Activities Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Business Overview Nature of Operations [Text Block] Schedule of accumulated other comprehensive loss Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Reclassification out of accumulated other comprehensive loss to net income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Annual Incentive Plan Annual Incentive Plan [Member] Annual Incentive Plan [Member] 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Intelligence Clients [Member] Intelligence Clients [Member] Civil Clients Civil Clients [Member] Civil Clients [Member] Global Commercial Clients Global Commercial Clients [Member] Global Commercial Clients [Member] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] UNITED STATES UNITED STATES Contract with Customer, Sales Channel [Axis] Contract with Customer, Sales Channel [Axis] Customer [Domain] Contract with Customer, Sales Channel [Domain] Prime Contractor Sales Channel, Directly to Consumer [Member] Sub-contractor Sales Channel, Through Intermediary [Member] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Total revenue (as a percent) Revenue From Contract With Customer, Excluding Assessed Tax, Percentage Revenue From Contract With Customer, Excluding Assessed Tax, Percentage Income Tax Disclosure [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Domain] Adjustments for Change in Accounting Principle [Domain] Revenue Recognition For Income Tax Purposes, Unbilled Receivables Revenue Recognition For Income Tax Purposes, Unbilled Receivables [Member] Revenue Recognition For Income Tax Purposes, Unbilled Receivables [Member] Revenue Recognition For Income Tax Purposes, Internally Developed Software Revenue Recognition For Income Tax Purposes, Internally Developed Software [Member] Revenue Recognition For Income Tax Purposes, Internally Developed Software [Member] Tax Period [Axis] Tax Period [Axis] Tax Period [Domain] Tax Period [Domain] Tax Years 2013-2015 Tax Years 2013-2015 [Member] Tax Years 2013-2015 [Member] Tax Years 2016-2018 Tax Years 2016-2018 [Member] Tax Years 2016-2018 [Member] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Income tax benefit Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Income tax assessments Income Tax Examination, Estimate of Possible Loss Income tax uncertainty Liability for Uncertainty in Income Taxes, Noncurrent Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Contract assets: Contract with Customer, Asset, Net [Abstract] Current Contract with Customer, Asset, Net, Current Long-term Contract with Customer, Asset, Net, Noncurrent Total Contract with Customer, Asset, Net Contract liabilities: Contract with Customer, Liability [Abstract] Advance payments, billings in excess of costs incurred and deferred revenue Contract with Customer, Liability Components of net postretirement medical expense Schedule of Net Benefit Costs [Table Text Block] Accounting Estimates Use of Estimates, Policy [Policy Text Block] Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Document and Entity Information [Abstract] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Listings [Table] Entity Listings [Table] Non-voting common stock, Class B Common Class B [Member] Restricted common stock, Class C Common Class C [Member] Special voting common stock, Class E Common Class E [Member] Classification of common stock that has different rights than Common Class A, B or C shares, representing the voting rights that accompany options that were issued in exchange for old stock rights that existed prior to the merger with The Carlyle Group. Entity Listings [Line Items] Entity Listings [Line Items] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Cost of revenue Cost of Sales [Member] General and administrative expenses General and Administrative Expense [Member] Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Stock-based compensation expense Allocated Share-based Compensation Expense Schedule of Common Stock Outstanding Schedule of Common Stock Outstanding Roll Forward [Table Text Block] Income Statement [Abstract] Operating costs and expenses: Costs and Expenses [Abstract] Cost of revenue Cost of Goods and Services Sold Billable expenses Billable Expenses Billable expenses include direct subcontractor expenses, travel expenses, and other expenses incurred to perform on contracts. General and administrative expenses General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Total operating costs and expenses Costs and Expenses Operating income Interest expense Other income (expense), net Other Nonoperating Income (Expense) Income before income taxes Income tax expense Earnings per common share (Note 4): Current assets Contract with Customer, Asset, Net, Current [Abstract] Accounts receivable–billed Billed Contracts Receivable Accounts receivable–unbilled Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Accounts receivable, net of allowance Other long-term assets Contract with Customer, Asset, Net, Noncurrent [Abstract] Accounts receivable–unbilled Total accounts receivable, net Accounts Receivable, Net Provision for doubtful accounts Provision for Doubtful Accounts Summary of Stock-Based Compensation Expense Recognized in the Condensed Consolidated Statements of Operations Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Schedule of Unrecognized Compensation Cost Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block] Summary of Grants of Restricted Stock Units and Restricted Stock Awards Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Income Taxes Income Tax Disclosure [Text Block]