v3.10.0.1

Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands			3 Months Ended			9 Months Ended
	Sep. 09, 2018	Jan. 06, 2017	Sep. 28, 2018	Sep. 29, 2017	Mar. 31, 2017	Sep. 28, 2018	Sep. 29, 2017	Jan. 01, 2018	Dec. 31, 2017
Basis of Presentation [Line Items]
Unbilled receivables restructuring costs incurred			$ 6,000			$ 6,000			$ 9,000
Anti-dilutive securities			0	0		71	10,949
Working capital adjustments finalized				$ 2,000
Long-term assets held for sale					$ 2,000
Accumulated depreciation					1,000
Gain on sale of long-term assets						$ (69)	$ 306
Selling, General and Administrative Expenses [Member]
Basis of Presentation [Line Items]
Gain on sale of long-term assets					1,000
International Resources Group Ltd. [Member]
Basis of Presentation [Line Items]
Initial purchase price		$ 25,000
Cash on hand adjustment purchase price				$ 1,000
Indemnity escrow					$ 2,000
Accounting Standards Update 2014-09 [Member] \| Accumulated Deficit [Member]
Basis of Presentation [Line Items]
Cumulative effect of change in accumulated deficit								$ 300
Merger Agreement [Member]
Basis of Presentation [Line Items]
Common stock exchange ratio	450
Transaction costs associated with pending merger	$ 5,000
Engility Corporation [Member]
Basis of Presentation [Line Items]
Capital stock owning percentage by parent			100.00%			100.00%
Forfeiture Support Associates LLC [Member]
Basis of Presentation [Line Items]
Non-controlling equity interest ownership percentage			50.10%			50.10%

[Line Items] for Basis of Presentation [Table]

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Common stock exchange ratio.

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New accounting pronouncement or change in accounting principle cumulative effect of change in accumulated deficit.

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Noncontrolling equity interest ownership percentage.

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Unbilled receivables restructuring costs incurred.

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Working capital adjustments.

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, excluding oil and gas property and timber property.

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Engility Holdings, Inc. 10-Q