Long-term Debt and Interest Rate Swap - Schedule of Debt (Details) - Vencore Holding Corp. and KGS Holding Corp. - USD ($) $ in Thousands	Mar. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Discount	$ (15,071)	$ (16,770)	$ (21,970)
Deferred financing	(5,070)	(5,489)	(5,493)
Current portion	(23,338)	(23,338)	(18,244)
Long‑term debt, net of current portion	$ 945,660	$ 947,678	$ 859,980
UBS First Lien
Debt Instrument [Line Items]
Interest Rate	6.44%	6.08%	5.75%
Total debt	$ 540,689	$ 542,137	$ 547,928
Cortland First Lien
Debt Instrument [Line Items]
Interest Rate	7.73%	7.35%	0.00%
Total debt	$ 204,250	$ 206,938	$ 0
UBS Second Lien
Debt Instrument [Line Items]
Interest Rate	10.44%	10.08%	9.75%
Total debt	$ 244,200	$ 244,200	$ 244,200
UBS / B1 loans
Debt Instrument [Line Items]
Interest Rate			7.75%
Total debt	$ 0	$ 0	$ 113,559

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount.

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-SubTopic 30
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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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