Engility 10-K 2 Mar 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 26, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	Engility Holdings, Inc.
Entity Central Index Key	1,544,229
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	EGL
Amendment Flag	false
Entity Common Stock, Shares Outstanding		36,860,915
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 504,983,723

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 41,890	$ 48,236
Receivables, net	331,094	334,248
Assets held for sale, current		20,242
Other current assets	19,681	30,404
Total current assets	392,665	433,130
Property, plant and equipment, net	44,006	46,547
Goodwill	1,071,371	1,078,454
Identifiable intangible assets, net	361,410	393,891
Deferred tax assets	150,535	232,283
Assets held for sale		11,962
Other assets	6,021	2,292
Total assets	2,026,008	2,198,559
Current liabilities:
Current portion of long-term debt	26,947	26,947
Accounts payable, trade	52,954	43,943
Accrued employment costs	77,545	98,860
Accrued expenses	74,856	76,870
Advance payments and billings in excess of costs incurred	30,380	33,259
Income tax liabilities	548	209
Liabilities held for sale, current		4,341
Other current liabilities	26,688	36,410
Total current liabilities	289,918	320,839
Long-term debt	938,687	1,039,993
Income tax liabilities	62,219	64,852
Liabilities held for sale		1,084
Other liabilities	59,079	66,986
Total liabilities	1,349,903	1,493,754
Commitments and contingencies (Note 9)
Equity:
Preferred stock, par value $0.01 per share, 25,000 shares authorized, none issued or outstanding as of December 31, 2017 or 2016
Common stock, par value $0.01 per share, 175,000 shares authorized, 36,822 and 36,776 shares issued and outstanding as of December 31, 2017 and 2016, respectively	368	368
Additional paid-in capital	1,244,940	1,237,826
Accumulated deficit	(576,019)	(541,702)
Accumulated other comprehensive loss	(3,805)	(4,865)
Non-controlling interest	10,621	13,178
Total equity	676,105	704,805
Total liabilities and equity	$ 2,026,008	$ 2,198,559

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	25,000,000	25,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (shares)	175,000,000	175,000,000
Common stock, shares issued (shares)	36,822,000	36,776,000
Common stock, shares outstanding (shares)	36,822,000	36,776,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands	Nov. 30, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue			$ 1,931,887,000	$ 2,076,423,000	$ 2,085,623,000
Costs and expenses
Cost of revenue			1,655,729,000	1,777,844,000	1,779,709,000
Selling, general and administrative expenses			142,391,000	166,238,000	203,262,000
Goodwill impairment	$ 0	$ 292,000,000	7,083,000	9,875,000	292,100,000
Total costs and expenses			1,805,203,000	1,953,957,000	2,275,071,000
Operating income (loss)			126,684,000	122,466,000	(189,448,000)
Interest expense, net			76,716,000	131,185,000	110,143,000
Other expenses (income), net			227,000	80,000	(1,285,000)
Income (loss) before provision for income taxes			49,741,000	(8,799,000)	(298,306,000)
Provision (benefit) for income taxes			80,356,000	(2,730,000)	(68,067,000)
Net loss			(30,615,000)	(6,069,000)	(230,239,000)
Less: Net income attributable to non-controlling interest			4,576,000	4,738,000	5,113,000
Net loss attributable to Engility			$ (35,191,000)	$ (10,807,000)	$ (235,352,000)
Loss per share attributable to Engility
Basic			$ (0.96)	$ (0.29)	$ (7.02)
Diluted			$ (0.96)	$ (0.29)	$ (7.02)
Weighted average number of shares outstanding
Basic			36,838	36,730	33,536
Diluted			36,838	36,730	33,536

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (30,615)	$ (6,069)	$ (230,239)
Other comprehensive income, net of tax:
Pension liability adjustment, net of tax expense of $528, $73 and $531 for the year ended December 31, 2017, 2016 and 2015, respectively	895	351	469
Less: reclassification adjustment for costs realized in net income, net of tax benefit of $148, $114 and $123 for the year ended December 31, 2017, 2016 and 2015, respectively	(231)	(178)	(108)
Net pension liability adjustment	664	173	361
Unrealized gain on derivative instruments, net of tax expense of $260, $2,880 and $2,250 for the year ended December 31, 2017, 2016 and 2015, respectively	401	4,514	3,526
Less: reclassification adjustment for costs realized in net income, net of tax benefit of $4, $1,482 and $1,339 for the year ended December 31, 2017, 2016 and 2015, respectively	(5)	(2,323)	(2,098)
Net unrealized gain on derivative instruments	396	2,191	1,428
Other comprehensive income, net of tax	1,060	2,364	1,789
Comprehensive loss	(29,555)	(3,705)	(228,450)
Less: Net income attributable to non-controlling interest	4,576	4,738	5,113
Comprehensive loss attributable to Engility	$ (34,131)	$ (8,443)	$ (233,563)

Consolidated Statements of Com6

Consolidated Statements of Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Pension liability adjustment, tax expense	$ 528	$ 73	$ 531
Pension liability, reclassification adjustment, tax benefit	148	114	123
Unrealized gain on derivative instruments, tax expense	260	2,880	2,250
Unrealized gain on derivative instruments, reclassification adjustment, tax benefit	$ 4	$ 1,482	$ 1,339

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Non-Controlling Interest [Member]
Beginning Balance at Dec. 31, 2014	$ 476,753	$ 176	$ 770,764	$ (295,543)	$ (9,018)	$ 10,374
Beginning balance (in shares) at Dec. 31, 2014		17,592
Net loss attributable to Engility	(235,352)			(235,352)
Other comprehensive income, net	1,789				1,789
Shares issued for acquisition	663,125	$ 189	662,936
Shares issued for acquisition (in shares)		18,938
Option price adjustment	228		228
Transaction costs	(2,590)		(2,590)
Dividends paid or accrued, net of forfeitures	(206,839)		(206,839)
Share-based compensation	9,300	$ 3	9,297
Share-based compensation (in shares)		186
Proceeds from share-based payment arrangements	279		279
Proceeds from share-based payment arrangements (in shares)		19
Payment of employee withholding taxes on restricted stock units	(8,021)		(8,021)
Excess tax deduction from share- based payment arrangements	5,530		5,530
Net income attributable to non- controlling member	5,113					5,113
Distribution to non-controlling interest member	(3,182)					(3,182)
Ending Balance at Dec. 31, 2015	706,133	$ 368	1,231,584	(530,895)	(7,229)	12,305
Ending balance (in shares) at Dec. 31, 2015		36,735
Net loss attributable to Engility	(10,807)			(10,807)
Other comprehensive income, net	2,364				2,364
Dividends forfeited	53		53
Share-based compensation	8,255		8,255
Share-based compensation (in shares)		17
Proceeds from share-based payment arrangements	214		214
Proceeds from share-based payment arrangements (in shares)		24
Payment of employee withholding taxes on restricted stock units	(1,779)		(1,779)
Excess tax deduction from share- based payment arrangements	(501)		(501)
Net income attributable to non- controlling member	4,738					4,738
Distribution to non-controlling interest member	(3,865)					(3,865)
Ending Balance at Dec. 31, 2016	$ 704,805	$ 368	1,237,826	(541,702)	(4,865)	13,178
Ending balance (in shares) at Dec. 31, 2016	36,776	36,776
Net loss attributable to Engility	$ (35,191)			(35,191)
Other comprehensive income, net	1,060				1,060
Dividends forfeited	41		41
Share-based compensation	7,938		7,938
Share-based compensation (in shares)		46
Adoption of employee share-based payment accounting standard	1,510		636	874
Payment of employee withholding taxes on restricted stock units	(1,501)		(1,501)
Net income attributable to non- controlling member	4,576					4,576
Distribution to non-controlling interest member	(7,133)					(7,133)
Ending Balance at Dec. 31, 2017	$ 676,105	$ 368	$ 1,244,940	$ (576,019)	$ (3,805)	$ 10,621
Ending balance (in shares) at Dec. 31, 2017	36,822	36,822

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net loss	$ (30,615,000)	$ (6,069,000)	$ (230,239,000)
Goodwill impairment charge	7,083,000	9,875,000	292,100,000
Share-based compensation	7,938,000	8,255,000	9,297,000
Depreciation and amortization	44,572,000	46,797,000	58,435,000
Loss on sale of business	1,062,000
Loss (gain) on sale of property, plant and equipment	(302,000)	1,078,000	3,413,000
Bad debt expense		744,000	7,346,000
Loss on extinguishment of debt	432,000	4,642,000
Amortization of bank debt fees	8,710,000	5,564,000	13,339,000
Deferred income taxes	82,813,000	1,256,000	(37,487,000)
Excess tax deduction on share-based compensation	(191,000)		5,530,000
Changes in operating assets and liabilities:
Receivables	3,142,000	31,882,000	46,338,000
Other assets	9,024,000	(986,000)	26,553,000
Accounts payable, trade	8,817,000	(9,673,000)	(33,570,000)
Accrued employment costs	(21,315,000)	17,149,000	(58,467,000)
Accrued expenses	(1,903,000)	1,805,000	(22,204,000)
Advance payments and billings in excess of costs incurred	(2,879,000)	(15,674,000)	8,901,000
Other liabilities	(18,715,000)	(2,240,000)	(35,337,000)
Net cash provided by operating activities	97,673,000	94,405,000	53,948,000
Investing activities:
Acquisitions, net of cash acquired			25,478,000
Proceeds from sale of business, net of amount placed in escrow	22,349,000
Proceeds from sale of property, plant and equipment	2,902,000
Capital expenditures	(9,691,000)	(21,446,000)	(19,610,000)
Net cash provided by (used in) investing activities	15,560,000	(21,446,000)	5,868,000
Financing activities:
Gross borrowings from issuance of long-term debt		1,180,000,000	585,000,000
Repayment of long-term debt	(110,447,000)	(1,215,754,000)	(403,674,000)
Gross borrowings from revolving credit facility	318,500,000	137,000,000	157,000,000
Gross repayments of revolving credit facility	(318,500,000)	(137,000,000)	(115,000,000)
Debt issuance costs		(9,988,000)	(42,425,000)
Equity issuance costs			(2,590,000)
Proceeds from share-based payment arrangements		214,000	279,000
Payment of employee withholding taxes on share-based compensation	(1,501,000)	(1,779,000)	(8,021,000)
Dividends paid	(407,000)	(1,709,000)	(204,304,000)
Distributions to non-controlling interest member	(7,133,000)	(3,865,000)	(3,182,000)
Net cash used in financing activities	(119,488,000)	(52,881,000)	(36,917,000)
Change in cash for assets held for sale	(91,000)	(1,864,000)
Net change in cash and cash equivalents	(6,346,000)	18,214,000	22,899,000
Cash and cash equivalents, beginning of period	48,236,000	30,022,000	7,123,000
Cash and cash equivalents, end of period	41,890,000	48,236,000	30,022,000
Non-cash investing activity:
Fair value of equity consideration paid for acquisition			663,125,000
Supplemental cash flow disclosure:
Cash paid for taxes	592,000	1,071,000	4,866,000
Cash paid for interest	$ 69,073,000	$ 106,205,000	$ 134,487,000

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	1. Basis of Presentation Description of Business: Engility Holdings, Inc. (Engility) has provided mission critical services to the U.S. government for more than 60 years. Engility offers a broad range of highly technical services, leveraging our strengths in systems engineering, cybersecurity, high performance computing, enterprise modernization, and training and mission operations to solve our customers’ most difficult challenges. Engility has a diversified portfolio that serves the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and space-related and intelligence community agencies, including the Central Intelligence Agency (CIA), the National Security Agency (NSA), the National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), National Aeronautical and Space Administration (NASA) and U.S Air Force Space Command (AFSPC). As used herein, the terms “Engility,” the “Company,” “we,” “us” or “our” refers to (i) Engility and its subsidiaries, for all periods prior to the closing of the TASC, Inc. (TASC) acquisition, and (ii) New Engility and its subsidiaries, for all periods following the TASC acquisition. The TASC acquisition was effected through a new holding company named New East Holdings, Inc. (New Engility). As a result of the business combination, New Engility succeeded to and continues to operate, directly or indirectly, the existing business of Engility and, indirectly, acquired the existing business of TASC. As of December 31, 2017, we employed approximately 8,700 individuals globally and operated in 44 countries. Engility has no operations other than owning 100% of the capital stock of Engility Corporation (formerly TASC, Inc.), a Massachusetts corporation (Engility Corporation), and the consolidated financial statements of Engility and its consolidated subsidiaries are identical in all respects to the consolidated financial statements of Engility Corporation and its consolidated subsidiaries. On July 17, 2012, L3 Technologies, Inc. completed the spin-off of Engility Holdings, Inc. from L3. Unless the context indicates otherwise, (i) references to Engility, the Company, we, us or our refer to Engility Holdings, Inc. and its subsidiaries and (ii) references to L3 refer to L3 Communications Holdings and its subsidiaries. Summary of Significant Accounting Policies Principles of Consolidation and Combination and Basis of Presentation: The Consolidated Financial Statements are prepared in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP) and reflect the financial position, results of operations and cash flows of Engility as a separate standalone entity. The Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. On January 31, 2014 and February 26, 2015, we completed the acquisitions of Dynamics Research Corporation (DRC) and TASC, respectively, which are more fully described in Note 3. These transactions were recorded using the purchase method of accounting; accordingly, DRC's and TASC's financial results are included in the Consolidated Financial Statements for the periods subsequent to the acquisition. Non-controlling Interest: Engility holds a 50.1% majority interest in Forfeiture Support Associates J.V. (FSA). The results of operations of FSA are included in Engility’s Consolidated Statements of Operations. The non-controlling interest reported on the Consolidated Balance Sheets represents the portion of FSA’s equity that is attributable to the non-controlling interest. Accounting Estimates: The preparation of financial statements in conformity with GAAP requires management to make estimates using assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. The most significant of these estimates relate to revenue recognition, recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income taxes, pension and defined benefit plan obligations and contingencies. Actual results experienced by the Company may differ materially from management's estimates. Out-of-period adjustments: During 2016, the Company recorded out-of-period adjustments that decreased pre-tax income by $2 million to correct errors related to the year ended December 31, 2015. The adjustments were not material to 2016 or any previously issued financial statements. Revenue Recognition: Substantially all of the Company’s revenue is derived from services provided to the U.S. government and its agencies, primarily by the Company’s consulting staff and, to a lesser extent, subcontractors. The Company generates its revenue from the following types of contractual arrangements: cost-reimbursable-plus-fee contracts, time-and-materials contracts, and fixed-price contracts. Revenue on cost-reimbursable-plus-fee contracts is recognized as services are performed, generally based on allowable costs plus any recognizable earned fee. The Company considers fixed fees under cost-reimbursable-plus-fee contracts to be earned in proportion to the allowable costs incurred in performance of the contract. For cost-reimbursable-plus-fee contracts that include performance-based fee incentives, which are principally award fee arrangements, revenue and profit on award fees are recognized as work on the contracts is performed. We have significant history with the client for the majority of these contracts, and that history and management’s evaluation and monitoring of performance form the basis of estimated fees recorded. Estimates of the total fee to be earned are made based on contract provisions, prior experience with similar contracts or clients, and management’s evaluation of the performance on such contracts. Revenue for time-and-materials contracts is recognized as services are performed, generally on the basis of contract allowable labor hours worked multiplied by the contract-defined billing rates, plus allowable direct costs and indirect cost allocations associated with materials used and other direct expenses incurred in connection with the performance of the contract. Revenue on fixed-price contracts is recognized using a percentage-of-completion method based on actual costs incurred relative to total estimated costs for the contract. These estimated costs are updated during the term of the contract, and may result in revision by the Company of recognized revenue and estimated costs in the period in which they are identified by cumulative catch-up adjustments. Profits on fixed-price contracts result from the difference between incurred costs and revenue earned. Percentage-of-completion contract accounting requires significant judgment relative to assessing risks, estimating contract revenue and costs, and making assumptions for schedule and technical issues. Due to the size and nature of many of our contracts, developing total revenue and cost at completion estimates require the use of significant judgment. Contract costs include direct labor and billable expenses, an allocation of allowable indirect costs, and warranty obligations. Billable expenses are comprised of subcontracting costs and other direct costs that often include, but are not limited to, travel-related costs and telecommunications charges. We recognize revenue and billable expenses from these transactions on a gross basis. Assumptions regarding the length of time to complete the contract also include expected increases in wages and prices for materials. Estimates of total contract revenue and costs are monitored during the term of the contract and are subject to revision as the contract progresses. Anticipated losses on contracts are recognized in the period they are deemed probable and can be reasonably estimated. Anticipated contract losses recorded for both of the years ended December 31, 2017 and 2016 were $1 million and for the year ended December 31, 2015 were $2 million. For the year ended December 31, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $12 million, of which $3 million was directly related to favorable performance on contracts with award fees. Amounts related to changes in estimates at completion for the year ended December 31, 2016 represented a net increase to revenue and operating income of $18 million, of which $4 million was directly related to favorable performance on contracts with award fees. The Company’s contracts may include the delivery of a combination of one or more of the Company’s service offerings. In these situations, the Company determines whether such arrangements with multiple service offerings should be treated as separate units of accounting based on how the elements are bid or negotiated, whether the customer can accept separate elements of the arrangement, and the relationship between the pricing on the elements individually and combined. Included in unbilled receivables, a component of receivables, net, are certain restructuring costs related to the performance of our U.S. government contracts which are required to be recorded under GAAP but are not currently allocable to contracts. Such costs are expensed outside of our indirect rates and recognized as revenue for the portion we expect to be recoverable in our rates. At both December 31, 2017 and 2016 these receivables were approximately $9 million and $11 million, respectively, and are allocated to contracts when they are paid or otherwise agreed. We regularly assess the probability of recovery of these costs. This assessment requires us to make assumptions about the extent of cost recovery under our contracts and the amount of future contract activity. If the level of backlog in the future does not support the continued expensing of these costs, the profitability of our remaining contracts could be adversely affected. Revenue and profit in connection with contracts to provide services to the U.S. government that contain collection risk because the contracts are incrementally funded and subject to the availability of funds appropriated are deferred until a contract modification is obtained, indicating that adequate funds are available to the contract or task order. Cost of Revenue: Cost of revenue primarily consists of compensation expenses for program personnel, the fringe benefits associated with this compensation, other direct expenses incurred to complete programs, including cost of materials and subcontract efforts. Selling, General, and Administrative Expenses: Selling, general and administrative expenses are expensed as incurred. Share-Based Compensation: Certain key employees of Engility participate in share-based compensation plans. We follow the fair value based method of accounting for share-based employee compensation, which requires us to expense all share-based employee compensation. We issue performance shares and restricted stock units (RSUs) under our existing plans to employees of the Company. Compensation expense is recognized for the entire award, net of estimated forfeitures, on a straight line basis over the requisite service period, which is generally three years, based on the grant date fair value. Income Taxes: We account for income taxes using the asset and liability method. Under this method, deferred tax assets and liabilities are recorded for the future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a tax rate change on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (the “Tax Act”). Further information on the tax impacts of the Tax Reform Act is included in Note 7 of the Company’s consolidated financial statements. In evaluating our ability to recover our deferred tax assets, in full or in part, we consider all available positive and negative evidence, including our past operating results, and our forecast of future earnings, future taxable income and prudent and feasible tax planning strategies. The assumptions utilized in determining future taxable income require significant judgment and are consistent with the plans and estimates we are using to manage the underlying business. Actual operating results in future years could differ from our current assumptions, judgments and estimates. However, we believe that it is more likely than not that most of the deferred tax assets recorded on our Consolidated Balance Sheet will ultimately be realized. We record a valuation allowance to reduce our deferred tax assets to the net amount that we believe is more likely than not to be realized. At December 31, 2017 the valuation allowance of $1 million was related to a portion of state deferred tax assets, foreign tax credits and charitable donations that we are not expected to realize. At December 31, 2017 and 2016, we had long-term net deferred tax assets of $151 million and $232 million, respectively. Cash and Cash Equivalents: Cash and cash equivalents represent cash that is directly attributable to the Company. Cash equivalents consist of highly liquid investments with an original maturity of three months or less at the time of purchase. Property, Plant and Equipment: Property, plant and equipment are stated at cost, less accumulated depreciation. Depreciation is computed by applying the straight-line method to the estimated useful lives of the related assets. Useful lives for buildings are 30 years. Useful lives for leasehold improvements and machinery, equipment, furniture and fixtures range from 3 to 10 years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the improvements. When property or equipment is retired or otherwise disposed of, the net book value of the asset is removed from our balance sheet and the net gain or loss is included in the determination of operating income. Maintenance and repairs are charged to expense as incurred. Goodwill: We record goodwill in connection with the acquisition of businesses when the purchase price exceeds the fair values of the assets acquired and liabilities assumed. Generally, the largest intangible assets from the businesses that we acquire are the assembled workforces, which includes the human capital of the management, administrative, marketing and business development, engineering and technical employees of the acquired businesses. The success of our businesses, including our ability to retain existing business (revenue arrangements) and to compete successfully for and win new business (revenue arrangements), is primarily dependent on the management, marketing and business development, contracting, engineering and technical skills and knowledge of our employees, rather than on productive capital (plant and equipment, and technology and intellectual property). Additionally, for a significant portion of our businesses, our ability to attract and retain employees who have U.S. government security clearances, particularly those of top-secret and above, is critical to our success, and is often a prerequisite for retaining existing revenue arrangements and pursuing new ones. Therefore, because intangible assets for assembled workforces are part of goodwill in accordance with the accounting standards for business combinations, the substantial majority of the intangible assets for our business acquisitions are recognized as goodwill. Additionally, the value assigned to goodwill for our business acquisitions also includes the value that we expect to realize from cost reduction measures that we implement for our acquired businesses. The carrying value of goodwill is not amortized, but is tested for impairment annually as of November 30 as well as whenever events or changes in circumstances indicate that the carrying amount of a reporting unit may not be recoverable. A reporting unit is an operating segment, as defined by the segment reporting accounting standards, or a component of an operating segment. A component of an operating segment is a reporting unit if the component constitutes a business for which discrete financial information is available and is reviewed by operating segment management. The process of an impairment test is to identify any potential impairment by comparing the carrying value of a reporting unit including goodwill and its fair value. We determine the fair value of the reporting units using a hybrid method valuation approach which includes (1) the Income Approach (also referred to as a discounted cash flow or DCF), and (2) the Guideline Public Company Method. An impairment charge is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value, however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Identifiable Intangible Assets: As part of the accounting for our business acquisitions, identifiable intangible assets are recognized as assets if they arise from contractual or other legal rights, or if they are capable of being separated or divided from the acquired business and sold, transferred, licensed, rented or exchanged. We do not recognize any intangible assets apart from goodwill for the assembled workforces of our business acquisitions. Identifiable intangible assets include customer contractual relationships, contractual backlog and technology. The initial measurement of these intangible assets is based on their fair values. The most significant identifiable intangible asset that is separately recognized for our business acquisitions is customer contractual relationships. All of our customer relationships are established through written customer contracts (revenue arrangements). The fair value for customer contractual relationships is determined, as of the date of acquisition, based on estimates and judgments regarding expectations for the estimated future after-tax earnings and cash flows (including cash flows for working capital) arising from the follow-on revenue on contract (revenue arrangement) renewals expected from the customer contractual relationships over their estimated lives, including the probability of expected future contract renewals and revenue, less a contributory assets charge, all of which is discounted to present value. Identifiable intangible assets are: (1) tested for impairment whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable and (2) amortized over their estimated useful lives as the economic benefits are consumed, ranging from 1 to 20 years. We evaluate the carrying amount and the remaining useful lives of identifiable intangible assets on a quarterly basis at the asset group level. To the extent events or changes in circumstances indicate the carrying amount of these assets may not be recoverable, we test recoverability based on our projection of the undiscounted future operating cash flows of the related asset group. To the extent such projections indicate that future undiscounted cash flows are not sufficient to recover the carrying amount, we recognize a non-cash impairment charge to reduce the carrying amount to fair value. No impairment charges related to identifiable intangible assets were recorded in the three years ending December 31, 2017. To evaluate the reasonableness of the useful lives of the identifiable intangible assets on a quarterly basis, the Company considers whether there have been any significant changes to the nature of the customer contractual relationships, including customers served by Engility, contract types and nature of work performed, subsequent to the date the intangibles were acquired. Assets and Liabilities Held for Sale: The Company entered into two separate agreements during the second half of 2016 to sell certain assets and liabilities owned by the Company both of which were completed in the first quarter of 2017. Depreciation for these assets ceased on the date they were designated as held for sale. The held for sale assets and liabilities were recorded at the lower of carrying value or estimated fair value, less an estimate of costs to sell. The estimate of fair value included unobservable inputs (Level 3 fair value). These assets and liabilities were designated as assets held for sale and liabilities held for sale in the accompanying consolidated balance sheets as of December 31, 2016. On January 6, 2017, the Company completed the sale of its international development services business, International Resources Group Ltd. (IRG), for an initial purchase price of $25 million in cash, subject to a cash on hand adjustment of $1 million finalized in the third quarter of 2017 and working capital adjustments that were finalized in January 2018 for approximately $2 million. As a result of the working capital adjustments, the Company recorded a loss of approximately $1 million at December 31, 2017. The sale was the result of the Company’s strategic review of its businesses and determination that the USAID portion of the Company’s international business no longer closely aligned with the Company’s future strategic direction. The Company used the proceeds from this sale, less an indemnity escrow of approximately $2 million, in the first quarter of 2017, to pay down existing debt. The Company expects to receive the indemnity escrow on or about the second anniversary of the sale assuming no claims are made against the escrow funds. In connection with the sale of IRG, and based on the final selling price of the business being less than carrying value of the assets as of December 31, 2016, the Company recorded a non-cash goodwill impairment charge of $10 million in 2016. During the first quarter of 2017, the Company completed its sale of long-term assets with carrying value totaling $2 million (net of accumulated depreciation of $1 million). The carrying amounts of assets and liabilities that were classified as held for sale were as follows: December 31, 2016 Assets held for sale, current: Cash and cash equivalents $ 1,864 Receivables, net 14,886 Other current assets 3,492 Assets held for sale, current $ 20,242 Assets held for sale: Property, plant and equipment, net $ 868 Goodwill 4,849 Identifiable intangible assets, net 6,245 Assets held for sale $ 11,962 Liabilities held for sale, current: Accounts payable, trade $ 727 Accrued expenses 3,268 Advance payments and billings in excess of costs incurred 271 Other current liabilities 75 Liabilities held for sale, current $ 4,341 Liabilities held for sale: Other liabilities $ 1,084 Liabilities held for sale $ 1,084 Pension and Defined Benefit Plans: The Company measures plan assets and benefit obligations as of the date of its fiscal year end. Accounting and reporting for the Company's pension and defined benefit plans requires the use of assumptions, including but not limited to, a discount rate and an expected return on assets. These assumptions are reviewed at least annually based on reviews of current plan information and consultation with the Company's independent actuary and the plans’ investment advisor. If these assumptions differ materially from actual results, the Company's obligations under the pension and defined benefit plans could also differ materially, potentially requiring the Company to record an additional liability. The Company's pension and defined benefit plan liabilities are developed from actuarial valuations, which are performed each year. Derivative Instruments: The Company recognizes derivative instruments as either an asset or liability measured at its fair value. For derivative instruments that have been formally designated as a cash flow hedge, the effective portion of changes in the fair value of the derivative instruments are recorded in accumulated other comprehensive income (loss). Amounts in accumulated other comprehensive income (loss) are reclassified into earnings when interest expense on the underlying borrowings is recognized. The Company had entered into multiple interest rate swap contracts which reduced the exposure to variability in cash flows relating to interest payments on a portion of its outstanding debt payments. These interest rate contracts were designated as cash flow hedges. The effective portion of the derivative’s gain or loss was initially reported in accumulated other comprehensive income (loss) and would be subsequently reclassified into earnings in the same period or periods during which the hedged forecasted transaction affects earnings. The ineffective portion of the gain or loss of a cash flow hedge would be reported in earnings. Fair Value Measurements: The Company utilizes fair value measurement guidance prescribed by GAAP to value its financial instruments. The guidance includes a definition of fair value, prescribes methods for measuring fair value, establishes a fair value hierarchy based on the inputs used to measure fair value and expands disclosures about the use of fair value measurements. Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. The carrying values of cash and cash equivalents, contract receivables and accounts payable approximate fair value because of the short-term nature of these instruments. The carrying value of the Term Loans, excluding original issue discount, and Notes approximated their fair value at December 31, 2017. The fair value of the Term Loans and Notes are based on quotes from a nationally recognized fixed income trading platform and is considered to be a Level 2 input, measured under GAAP hierarchy. Earnings per Share: Basic EPS is computed by dividing net income (loss) by the weighted average number of shares of common stock outstanding for the period. Diluted EPS reflects the weighted-average effect of all potentially dilutive securities outstanding during the periods. Diluted EPS includes the incremental effect of the employee stock purchase plan, restricted stock units, and stock options calculated using the treasury stock method. For the years ended December 31, 2017, 2016 and 2015, 532,060 shares, 766,935 shares and 570,181 shares, respectively, of common stock were not included in diluted EPS due to their anti-dilutive effects. The following table sets forth the reconciliation of the weighted average shares outstanding and calculation of EPS: Year Ended December 31, 2017 2016 2015 Net loss attributable to Engility $ (35,191 ) $ (10,807 ) $ (235,352 ) Weighted average number of shares outstanding – Basic 36,838 36,730 33,536 Dilutive effect of share-based compensation outstanding after application of the treasury stock method — — — Weighted average number of shares outstanding – Diluted 36,838 36,730 33,536 Loss per share attributable to Engility Basic $ (0.96 ) $ (0.29 ) $ (7.02 ) Diluted $ (0.96 ) $ (0.29 ) $ (7.02 )

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
New Accounting Pronouncements	2. New Accounting Pronouncements In September 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-13, Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842) In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In March 2017, the FASB issued ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The update requires employers to present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost, including interest cost, expected return on plan assets, amortization of prior service cost/credit and actuarial gain/loss, and settlement and curtailment effects, are to be presented outside of any subtotal of operating income. Employers will have to disclose the line(s) used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement. ASU 2017-07 is effective for fiscal years and interim periods beginning after December 15, 2017, and early adoption is permitted. The Company does not believe the adoption of this accounting standard will have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment, In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash—a consensus of the FASB Emerging Issues Task Force In August 2016, the FASB issued Accounting Standards Update ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting. In February 2016, the FASB issued ASU No. 2016-02, Leases In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross Versus Net) , Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing Revenue from Contracts with Customers (Topic 606): Narrow Scope Improvements and Practical Expedients; Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements, Income Statement – Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606). As the new standard impacts several of our business processes, systems and controls, the Company developed and implemented a comprehensive project plan to guide through the process of adopting the new standard. To assess the impact of adopting ASC 606, Engility reviewed its contract population by selecting samples upon which to perform detailed contract analyses. These contract analyses entailed reviewing each selected contract to determine the appropriate accounting treatment under ASC 606. These contract reviews were performed in a phased approach, enabling the Company to identify specific ASC 606-related risk areas for subsequent, more focused analyses. We will continue to recognize revenue and profit for the majority of our performance obligations over time as work is performed because the customer simultaneously receives and consumes the benefits provided by our performance and based upon the continuous transfer of control to the customer as costs are incurred. For U.S. government contracts, this continuous transfer of control to the customer is supported by clauses in the contract that allow the customer to unilaterally terminate the contract for convenience, pay us for costs incurred plus a reasonable profit and take control of any work in process. Engility management identified two primary areas likely to result in ASC 606-related impact: • Unfunded Performance Obligations - Revenue Recognition • Customized Products - Some of Engility’s contracts with customers entail building products to customer specifications. Under ASC 605, revenue for these customized products was recognized at the time of product delivery. Under ASC 606, the Company will change its revenue recognition methodology from point in time to over time for customized products, as they meet at least one of the overtime criteria. As Engility will adopt ASC 606 using the modified retrospective method, the Company must record a one-time cumulative impact of adoption at January 1, 2018. While we are still in the process of finalizing the impact of adoption, we currently estimate the cumulative impact will reduce accumulated deficit by less than $2 million, which management believes is not material.

Business Acquisitions

Business Acquisitions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Acquisitions	3. Business Acquisitions TASC Acquisition On February 26, 2015, we completed the acquisition of TASC, a leading professional services provider to the national security and public safety markets, in an all-stock transaction. We acquired TASC to further diversify our portfolio to add leading positions with U.S. national security and public safety agency customers, including, the NGA, DIA and other intelligence community agencies. We also added space-related agency customers such as the NRO, NASA and U.S. Air Force. The acquisition of TASC also enhanced our market position with DHS, DTRA, FAA, and MDA. The business combination was effected through New Engility. As a result of the business combination, New Engility succeeded to and continues to operate, directly or indirectly, the existing business of Engility and, indirectly, acquired the existing business of TASC. Accordingly, the combined companies now operate under New East Holdings, Inc. which was renamed “Engility Holdings, Inc.” upon the closing of the acquisition. The New Engility common stock, similar to the predecessor Engility common stock, trades on the New York Stock Exchange (NYSE) under the symbol “EGL.” As a result of the acquisition of TASC, former TASC stockholders now hold approximately 51% of our shares of common stock outstanding as of February 26, 2018. As a condition to the merger, we entered into a Stockholders Agreement, dated February 26, 2015 and amended as of February 28, 2018, with Birch Partners, LP (Birch), and for the limited purposes set forth therein, certain investment funds affiliated with Kohlberg Kravis Roberts & Co. L.P. (KKR) and certain investment funds affiliated with General Atlantic LLC (GA) (the Stockholders Agreement). The Stockholders Agreement establishes certain rights, restrictions and obligations of Birch, KKR and GA, and sets forth certain governance and other arrangements relating to Engility, including the right of Birch to designate (i) four directors for nomination to our board of directors for so long as each of KKR and GA (including their respective affiliates) beneficially own at least 50% of the shares of our common stock it owned as of the date of the Stockholders Agreement or (ii) two directors for nomination to our board of directors for so long as each of KKR and GA (including their respective affiliates) beneficially own at least 25% (but less than 50%) of the shares of our common stock it owned as of the date of the Stockholders Agreement. In connection with the acquisition, we issued 18,937,765 shares of Engility common stock on February 26, 2015 valued at approximately $663 million, and we assumed debt with an estimated fair value of $623 million. Engility declared a special cash dividend payable to stockholders of record as of immediately prior to the closing of the TASC transaction (the Cash Dividend), including holders of all outstanding RSUs and performance shares upon vesting, in the amount of $207 million, or $11.434 per share. For holders of unvested RSUs and performance shares, the Cash Dividend accrued on such grants and will be delivered to the holders upon the vesting of such grants. In connection with the acquisition, Engility has paid $204 million pursuant to the Cash Dividend to stockholders and holders of vested RSUs, performance share units and options. The remaining Cash Dividend balance will be paid to holders upon the vesting of their outstanding RSUs. We accounted for the acquisition of TASC as a business combination under ASC 805 with Engility as the accounting acquirer. We determined Engility was the accounting acquirer in accordance with ASC 805-10-25-5 as Engility gained control of TASC upon completion of the merger. To make this determination we considered factors as indicated in ASC 805-10-55, including which entity issued equity interests to effect the combination, board of director composition, stockholder ownership, voting control, restrictions on stockholder voting rights, anticipated management positions and the relative size of the two companies. Engility issued its equity to effect the combination, which is usually done by the acquirer. The board of directors immediately following the acquisition was comprised of eleven individuals, seven of whom were the Engility directors and the remaining four of whom were designated by Birch the holder of approximately 99% of the outstanding common stock of TASC Parent Corporation prior to the acquisition. While the stockholders of TASC Parent Corporation own approximately 52% of the combined company common stock following the closing of the transaction, Birch executed, at the closing of the transaction, a stockholders agreement agreeing to vote (i) until it no longer has any director nomination rights, with respect to the election of directors, all of its shares in the same manner as, and in the same proportion to, all shares as voted by Engility stockholders (excluding the votes of Birch), other than with respect to its four director nominees; and (ii) with respect to all other proposals, all of its shares in excess of 30% of the total voting power of all issued and outstanding shares of the combined company (between 21% and 21.5% initially) in the same manner as, and in the same proportion to, all shares as voted by Engility stockholders (excluding the votes of Birch). Thus, with respect to proposals other than the election of directors, Birch only controls and is able to independently vote an aggregate of 30% of the outstanding shares of the combined company. Birch is not be able to transfer ownership for years one through three following the closing of the transaction and is limited in years four through six. Following the acquisition, the combined Engility company was led by Engility’s legacy President and Chief Executive Officer, Anthony Smeraglinolo, and John Hynes, TASC’s former President and Chief Executive Officer, became the Chief Operating Officer of the combined company, reporting to Mr. Smeraglinolo. Another consideration was the relative size of the two companies. Engility had greater revenue, total assets, earnings before interest, taxes, depreciation, and amortization (EBITDA), pre-tax income and employees. All of the above mentioned factors have led us to conclude that Engility was the accounting acquirer. The final allocation of purchase price is as follows: Purchase Price Allocation Number of Engility shares issued 18,937,765 Share price on February 26, 2015 $ 46.45 Dividend payable to Engility stockholders 11.434 Value of Engility shares issued to TASC stockholders $ 35.016 Equity consideration $ 663,125 Cash $ 25,478 Receivables 149,041 Prepaid and deferred income taxes, current 26,015 Other current assets 26,286 Property, plant and equipment 15,835 Deferred tax assets 175,180 Other assets 5,096 Current portion of long-term debt (4,097 ) Accounts payable, trade (34,503 ) Accrued employment costs (92,396 ) Accrued expenses (33,387 ) Advance payments and billings in excess of costs incurred (18,004 ) Deferred income taxes, current and income taxes payable (248 ) Other current liabilities (32,522 ) Long-term debt (619,227 ) Other long-term liabilities (24,446 ) Identifiable intangible assets 358,300 Goodwill 740,724 $ 663,125 The goodwill arising from the TASC acquisition consists largely of the specialized nature of the workforce as well as the synergies and economies of scale expected from combining the operations of Engility and TASC and their respective subsidiaries. The goodwill arising from the TASC acquisition is not tax deductible. The valuation of the identified intangible assets acquired is summarized below: Identifiable Intangible Assets Useful Life (years) Customer contractual relationships 15 $ 333,600 Contractual backlog 1 17,700 Technology 15 7,000 Total intangible assets $ 358,300 From the date of acquisition, February 26, 2015, through December 31, 2015, TASC generated $907 million of revenue and operating income of $55 million. Acquisition and restructuring expenses related to our acquisitions for the year ended December 31, 2017, 2016 and 2015 were $5 million, $12 million and $45 million, respectively. Pro forma Results The following pro forma results of operations have been prepared as though the acquisition of TASC had occurred on January 1, 2014. These pro forma results include adjustments for (i) amortization expense for the estimated identifiable intangible assets in the preliminary allocation of purchase price, (ii) the removal of historical TASC amortization expense, (iii) adjustments to conform TASC policies to Engility's policies related to the timing and recognition of certain contract revenue and costs, (iv) the alignment of TASC’s financial calendar to that of Engility’s and (v) the removal of acquisition-related expenses incurred and recorded in each of TASC and Engility’s results of operations in the year ended December 31, 2015. The following pro forma results for the year ended December 31, 2015 do not purport to be indicative of the results of operations that would have been attained had the TASC acquisition been made as of January 1, 2014, or of results of operations that may occur in the future. Revenue $ 2,239,577 Operating (loss) income $ (143,496 )

Receivables

Receivables	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Receivables	4. Receivables The components of contract receivables are presented in the table below. December 31, 2017 2016 Billed receivables $ 119,506 $ 97,661 Unbilled receivables 222,994 248,253 Allowance for doubtful accounts (11,406 ) (11,666 ) Total receivables, net $ 331,094 $ 334,248 Virtually all of our revenue and related receivables relate to contracts with the U.S. government. Unbilled receivables principally consist of amounts to be billed within the next month, generally from cost-plus type contracts and time-and-material type contracts due to the timing of preparation of invoices to customers. Revenue recorded in excess of milestone billings on fixed-price type contracts consist of amounts not expected to be billed within the next month. Such amounts are converted to billed receivables when invoiced to customers according to contractual billing terms, which generally occur when performance milestones are completed. We believe that significantly all of the unbilled contract receivables at December 31, 2017 will be billed and collected within one year. We do not believe that we have significant exposure to credit risk as accounts receivable and the related unbilled amounts are due primarily from the U.S. government. The Company has credit risk with respect to foreign government customers which comprise approximately 4% of total receivables, net of advance payments, and has reserved for these balances accordingly. The allowance for doubtful accounts primarily represents our estimate for exposure to compliance, contractual issues and bad debts related to prime contractors and commercial customers. The following table details the allowance for doubtful accounts: Year Ended December 31, 2017 2016 2015 Balance at beginning of year $ 11,666 $ 11,480 $ 1,482 Charged to expense 12 744 10,286 Deductions (272 ) (558 ) (288 ) Balance at end of year $ 11,406 $ 11,666 $ 11,480 The increase in the allowance for doubtful accounts in 2015 was primarily driven by a reserve booked related to a dispute with a foreign government customer.

Goodwill and Identifiable Intan

Goodwill and Identifiable Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Identifiable Intangible Assets	5. Goodwill and Identifiable Intangible Assets The changes in the carrying amounts of goodwill were as follows: Goodwill Balance as of December 31, 2015 Goodwill $ 2,060,314 Accumulated impairment losses (967,136 ) 1,093,178 Impairment charge (9,875 ) Goodwill allocated to assets held for sale (4,849 ) Balance as of December 31, 2016 Goodwill 2,055,465 Accumulated impairment losses (977,011 ) 1,078,454 Impairment charge (7,083 ) Balance as of December 31, 2017 Goodwill 2,055,465 Accumulated impairment losses (984,094 ) $ 1,071,371 Goodwill Impairment Review We review goodwill for impairment annually as of November 30 and whenever events or changes in circumstances indicate that the carrying amount may not be recoverable for each reporting unit. The process of an impairment test is to identify any potential impairment by comparing the carrying value of a reporting unit including goodwill and its fair value. We use a hybrid method valuation approach to determine the fair value of the reporting units which includes (1) the Income Approach (also referred to as a discounted cash flow or DCF), which is dependent upon estimates for future revenue, operating income, depreciation and amortization, income tax payments, working capital changes, and capital expenditures, as well as, expected long-term growth rates for cash flows; and (2) the Guideline Public Company Method, which uses valuation metrics from similar publicly traded companies (i.e., small-to-mid-cap providers of services to the U.S. Federal and local governments). Both of these approaches are affected by economic conditions related to the U.S. defense industry as well as conditions in the U.S. capital markets. We evaluate the reasonableness of the fair value calculations of our reporting units by comparing the total of the fair values of all of our reporting units to our total market capitalization, taking into consideration an appropriate control premium. An impairment charge is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value, however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The fair value measurement was calculated using unobservable inputs to the discounted cash flow method, which are classified as Level 3 within the fair value hierarchy under GAAP. The key assumptions we used to estimate the fair values of the reporting units are: • Discount rates; • Compounded annual revenue growth rates; • Average operating margins; • Terminal value capitalization rate (capitalization rate); and • Guideline Company valuations. Of the key assumptions, the discount rates and the capitalization rate are market-driven. These rates are derived from the use of market data and employment of the capital asset pricing model. The company-dependent key assumptions are the compounded annual revenue growth rates and the average operating margins and are subject to much greater influence from our actions. We used discount rates that are commensurate with the risk and uncertainty inherent in the respective reporting units and in our internally-developed forecasts. Actual results may differ from those assumed in our forecasts and changes in assumptions or estimates could materially affect the determination of the fair value of a reporting unit, and therefore could affect the amount of potential impairment. We evaluate the reasonableness of the fair value calculations of our reporting units by reconciling the total of the fair values of all of our reporting units to our total market capitalization as of our impairment test date, taking into account an appropriate control premium. The determination of a control premium requires the use of judgment and is based upon control premiums observed in comparable market transactions. Inherent in our development of the present value of future cash flow projections are assumptions and estimates derived from a review of our expected revenue growth rates, profit margins, business plans, cost of capital, and tax rates. We also make assumptions about future market conditions, market prices, interest rates, and changes in business strategies. Changes in our assumptions or estimates could materially affect the determination of the fair value of a reporting unit and, therefore, could eliminate the excess of fair value over the carrying value of a reporting unit entirely and, in some cases, could result in impairment. Such changes in assumptions could be caused by a loss of one or more significant contracts, reductions in government and/or private industry spending, or a decline in the demand of our services due to changing economic conditions. Given the contractual nature of our business, if we are unable to win or renew contracts; are unable to estimate and control our contract costs; fail to perform adequately to our clients’ expectations; fail to procure third-party subcontractors, or fail to secure adequate funding for our projects, our profits, revenue and growth over the long-term would decline and such a decline could significantly affect the fair value assessment of the reporting units and cause our goodwill to become impaired. To determine fair value as of November 30, 2017 and 2016, we used the Income Approach and Guideline Public Company Method weighted 50% and 50%, respectively, which is consistent with prior periods. The two methods returned value indications that were supportive of one another and corroborative of the value conclusion. In the third quarter of 2017, Engility underwent an organizational realignment (the “2017 Realignment”) resulting in (i) the combination of the Products and DoD reporting units into a new Defense group reporting unit (effective on July 11, 2017) and (ii) the transfer of the operations of its Federal Civilian group to its remaining reporting units (effective on August 3, 2017). Since the new Defense group represents the combination, in full, of the Products and DoD reporting units, a fair value allocation of prior goodwill and intangible asset balances was not required. Instead, the allocation of goodwill to the Defense reporting unit was the combined balance of the prior two reporting units. The Company reallocated the goodwill and intangible assets assigned to the Federal Civilian group to their respective new reporting units based on relative fair values of the components of the Federal Civilian group that were realigned. Further, as part of this realignment, a new International reporting unit was created. Although the 2017 Realignment changed the structure of the business groups, it did not change how Engility operates its business groups, which continue to be organized around customers and have dedicated group-level senior vice presidents responsible for growth of their respective portfolios, customer relationships, project management and project profitability. In addition, the 2017 Realignment did not change the duties of our chief operating decision maker to evaluate consolidated financial information in order to allocate resources and assess performance. As a result, we determined that we have a single operating and reportable segment and consequently do not aggregate any operating segments. Goodwill Impairment Measurement Based on results of the November 30, 2017 goodwill impairment test, we recorded a non-cash impairment charge of $7 million related to the International reporting unit. The International reporting unit was formed in the third quarter of 2017 as a result of the reorganization of our Federal Civilian unit. The International reporting unit was highly concentrated on two primary contracts. As the Company’s annual operating and long term strategic plans were finalized in the fourth quarter of 2017, the Company determined that the International reporting unit’s long range outlook for profitability was lower and working capital requirements were higher. As a result of its high DSO, the International reporting unit’s carrying value at the time of the impairment test was higher than what was anticipated at the time of the 2017 Realignment. Given these factors and risk around the upcoming re-compete of one of the primary contracts within the reporting unit, certain valuation metrics for the International reporting unit were significantly less favorable. Based on results of the November 30, 2016 goodwill impairment test, the fair value for all five reporting units exceeded their carrying value; therefore, no impairment charge was required. However, in connection with the sale of IRG, and based on the final selling price of the business being less than carrying value of the assets as of December 31, 2016, the Company recorded a non-cash goodwill impairment charge of $10 million in 2016. During the fourth quarter of 2015, we recorded a non-cash goodwill impairment charge of $292 million due to the decline in the estimated fair value in four of the reporting units. The decline in the estimated fair value was primarily due to the continued impact from legacy contracts that are ending, reduced in-theater work, new business that did not materialize in the fourth quarter of 2015 and a corresponding reduction in estimated future cash flows. The more significant assumptions used in our DCF valuation to determine the fair value of the reporting units in connection with the goodwill valuation assessment at November 30, 2017 and 2016 were: (1) detailed three-year cash flow projections for the reporting units, which are based primarily on our estimates of future revenue, operating income and cash flows, (2) an expected long-term growth rate for the reporting units which reflects the expected long-term growth rate for the U.S. economy and respective areas of the U.S. defense industry in which the reporting units operate and (3) risk adjusted discount rates, which represents the estimated weighted-average cost of capital (WACC) for the reporting units and includes the estimated risk-free rate of return that is used to discount future cash flow projections to their present values. The reporting units WACC was comprised of were: (1) an estimated required rate of return on equity based on publicly traded companies with business and economic risk characteristics comparable to the reporting units (Market Participants) and (2) an after-tax rate of return on Market Participants’ debt, each weighted by the relative percentages of Market Participants’ equity and debt. The WACC is based on a number of market inputs that are outside of our control and are updated annually to reflect changes to such market inputs as of the date of our annual goodwill impairment assessments, including changes to: (1) the estimated required rate of return on equity based on historical returns on common stock securities of Market Participants and the Standard & Poor’s 500 Index (referred to as beta), (2) the risk free rate of return based on the prevailing market yield on the 20-year U.S. Treasury bond, (3) the Moody’s 20 year Baa rate, and (4) the relative percentages of Market Participants’ equity and debt. We consistently consider several factors to determine expected future annual cash flows for the reporting units, including historical multi-year average cash flow trends and the expected future cash flow growth rates primarily based on our estimates of future revenue, operating income, and working capital changes. Furthermore, the majority of the revenue for these reporting units is primarily dependent upon the DoD budget and spending. We closely monitor changes in these factors and their impact on the expected cash flow of the reporting units. Our DCF valuation is dependent upon several assumptions and is subject to uncertainties due to uncontrollable events, including future DoD budgets, U.S. government spending priorities for services and general economic conditions. A change in any one or a combination of the assumptions used in our DCF valuation could negatively impact the fair value, resulting in additional non-cash goodwill impairments. For the November 30, 2017 and 2016 goodwill impairment tests the weighted average long-term growth rate and WACC developed by management for purposes of our goodwill impairment analysis for both periods was 3% and 9%, respectively. The long term growth rate was evaluated considering the discrete projection period and long-term industry and economic factors. Other than the impaired International reporting unit, the fair value of each of the three remaining reporting units exceeded its carrying value by more than 20% as of November 30, 2017. For November 30, 2016, the fair value of each of our reporting units exceeded its carrying value by more than 15% as of November 30, 2016. The amount of goodwill for each of our reporting units is shown in the following table: December 31, 2017 2016 Space Systems $ 367,526 $ 288,594 Intelligence Solutions 318,242 260,129 Defense 385,603 242,243 International — N/A Federal Civilian N/A 187,582 Products N/A 99,906 Total $ 1,071,371 $ 1,078,454 Goodwill decreased in 2017 due to the impairment charge of $7 million to the International reporting unit as previously discussed above, which represented the full amount allocated to the International reporting unit in conjunction with the 2017 Realignment. Identifiable Intangible Assets Information on our identifiable intangible assets that are subject to amortization is presented in the table below. December 31, 2017 December 31, 2016 Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in years) Customer contractual relationships 17 $ 545,229 $ 189,497 $ 355,732 $ 545,229 $ 157,482 $ 387,747 Technology 15 7,000 1,322 5,678 7,000 856 6,144 Total $ 552,229 $ 190,819 $ 361,410 $ 552,229 $ 158,338 $ 393,891 In connection with the agreement to sell IRG, $9 million of the gross carrying amount of total identifiable intangible assets was allocated to the carrying value of assets held for sale in 2016 as well as the related accumulated amortization of $3 million. Our recorded amortization expense for our identifiable intangible assets is presented in the table below. Year Ended December 31, 2017 2016 2015 Amortization expense $ 32,481 $ 36,491 $ 45,222 Based on gross carrying amounts at December 31, 2017, our estimate of amortization expense for identifiable intangible assets are presented in the table below. Year Ended December 31, 2018 2019 2020 2021 2022 Amortization expense $ 32,482 $ 32,482 $ 32,482 $ 32,482 $ 32,482

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property, Plant and Equipment	6. Property, Plant and Equipment The components of property, plant and equipment are presented in the table below. December 31, 2017 2016 Land $ 900 $ 900 Buildings and improvements 850 850 Machinery, equipment, furniture and fixtures 31,208 28,622 Leasehold improvements 41,757 43,598 Assets under construction 3,606 1,861 Gross property, plant and equipment 78,321 75,831 Accumulated depreciation and amortization (34,315 ) (29,284 ) Property, plant and equipment, net $ 44,006 $ 46,547 Our recorded depreciation expense for property, plant and equipment assets is presented in the table below. Year Ended December 31, 2017 2016 2015 Depreciation expense $ 12,091 $ 10,306 $ 13,213

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	7. Income Taxes The Tax Act was signed into law on December 22, 2017. The Tax Act changed many aspects of U.S. corporate income taxation and included reduction of the corporate income tax rate from 35% to 21%. As a result, we recognized provisional tax effects in the year ended December 31, 2017 of $60 million in tax expense relating almost entirely to the remeasurement of our net deferred tax assets using the new 21% tax rate. Upon completion of our 2017 U.S. income tax return in 2018, we may identify additional remeasurement adjustments to our recorded net deferred tax assets and liabilities. We will continue to assess our provision for income taxes as future guidance is issued but do not currently anticipate significant revisions will be necessary. On December 22, 2017, Staff Accounting Bulletin No. 118 (SAB 118) was issued to address the application of US GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Tax Act. In accordance with SAB 118, the Company has determined that approximately $1 million related to foreign tax credits may not be realized and has maintained a valuation allowance. Additional work is necessary to do a more detailed analysis of historical foreign earnings as well as potential correlative adjustments. As mentioned above, additional remeasurement adjustments may result from our deferred taxes upon completion of the 2017 U.S. income tax return in 2018. Income (loss) before income taxes is summarized in the table below. Year Ended December 31, 2017 2016 2015 Domestic $ 49,114 $ (9,285 ) $ (298,644 ) Foreign 627 486 338 Income before income taxes $ 49,741 $ (8,799 ) $ (298,306 ) The components of our current and deferred portions of the provision for income taxes are presented in the table below. Year Ended December 31, 2017 2016 2015 Current income tax provision (benefit): Federal $ (2,678 ) $ (4,030 ) $ (29,632 ) State and local 301 107 (1,569 ) Foreign 105 (14 ) 727 Subtotal (2,272 ) (3,937 ) (30,474 ) Deferred income tax provision (benefit): Federal 84,464 2,252 (31,830 ) State and local (1,836 ) (1,089 ) (5,718 ) Foreign — 44 (45 ) Subtotal 82,628 1,207 (37,593 ) Total provision (benefit) for income taxes $ 80,356 $ (2,730 ) $ (68,067 ) A reconciliation of the statutory Federal income tax rate to our effective income tax rate is presented in the table below. Year Ended December 31, 2017 2016 2015 Statutory Federal income tax rate 35.0 % 35.0 % 35.0 % State and local income taxes, net of Federal income tax benefit 3.0 6.6 1.7 Goodwill impairment 5.0 (33.2 ) (18.0 ) Non-controlling interest (3.2 ) 18.8 0.6 Non-deductible acquisition costs 3.4 — (0.3 ) Federal tax credits (0.8 ) 2.5 0.1 Tax audit settlements and return adjustments 0.5 (3.3 ) — Uncertain tax positions (2.0 ) 1.3 3.9 Valuation allowance — 3.9 — Impacts of '17 Tax Cuts and Jobs Act 120.5 — — Other, net 0.1 (0.6 ) (0.2 ) Effective income tax rate 161.5 % 31.0 % 22.8 % The significant components of our deferred tax assets and liabilities are presented in the table below. December 31, 2017 2016 Deferred tax assets: Compensation and benefits $ 18,048 $ 26,371 Unrecognized tax benefits 30,331 32,808 Fixed assets 5,101 6,627 Deferred revenue 7,732 12,917 Reserves 8,115 14,396 Pension 10,138 17,958 Net operating losses 113,615 171,969 Income recognition on contracts in process 7,335 - Other 12,963 21,089 Gross deferred tax assets 213,378 304,135 Deferred tax liabilities: Goodwill and other intangible assets 54,754 49,976 Income recognition on contracts in process — 7,119 Other 7,015 13,769 Gross deferred tax liabilities 61,769 70,864 Valuation allowance (1,074 ) (988 ) Net deferred tax assets $ 150,535 $ 232,283 The valuation allowance on deferred tax assets of approximately $1 million as of December 31, 2017 and 2016 consists of state deferred tax assets, foreign tax credits and charitable donations. Included in the above table, we have approximately $1 million of foreign income tax credits that will expire beginning in 2025. We and our subsidiaries filed income tax returns in various state and foreign jurisdictions. The Company has available at December 31, 2017, unused Federal and state operating loss carry forwards of $436 million and $421 million, respectively, that may be applied against taxable income and that expire in the years as indicated in the table below. Year of Expiration Federal State 2018-2028 $ — $ 4,997 2029-2031 100,876 84,958 2032-2034 187,519 162,444 2035-2037 147,133 168,658 $ 435,528 $ 421,057 The following table presents a reconciliation of the beginning and ending amounts of unrecognized tax benefits, excluding potential interest and penalties: Year Ended December 31, 2017 2016 2015 Balance at January 1 $ 55,274 $ 58,360 $ 67,927 Additions/reductions for tax positions related to the current year 65 151 4,139 Additions/reductions for tax positions related to prior years — — (11,542 ) Lapse of statute of limitations (2,551 ) (3,237 ) (2,164 ) Balance at December 31 $ 52,788 $ 55,274 $ 58,360 The balance of unrecognized tax benefits, exclusive of interest and penalties, was $53 million, $55 million and $58 million at December 31, 2017, 2016 and 2015, respectively. At December 31, 2017, 2016 and 2015, we had $9 million, $10 million and $10 million of interest and penalty accrued related to unrecognized tax benefits. It is expected that $9 million of unrecognized tax benefits at December 31, 2017 would affect earnings if recognized. The statutes of limitations for our U.S. Federal income tax returns remain open for the years 2012 and onward. The statute of limitations for L3’s U.S. Federal income tax return for the year ended December 31, 2012 remains open as of December 31, 2017. Foreign and U.S. state jurisdictions have statutes of limitations generally ranging from three to five years. As of December 31, 2017, we anticipate that uncertain tax positions will decrease by approximately $27 million over the next 12 months of which $26 million relates to the resolution of a foreign uncertain tax position. The reversal of the foreign reserve will have a net impact of between $2 million and $3 million benefiting our provision for income taxes in the period resolved. The actual amount could vary significantly depending on the ultimate timing and nature of any settlements. At December 31, 2017 and 2016, non-current income taxes payable included accrued potential interest of $9 million and 10 million, respectively. With respect to the interest related items, our income tax provision included a benefit of $1 million, $1 million and $2 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	8. Share-Based Compensation Share-based compensation expense is summarized in the table below. Year Ended December 31, 2017 2016 2015 Share-based compensation $ 7,938 $ 8,255 $ 9,297 Income taxes (3,107 ) (3,219 ) (3,622 ) Total after income taxes $ 4,831 $ 5,036 $ 5,675 As of December 31, 2017, there was $9 million of total unrecognized compensation cost related to unvested stock compensation arrangements. This cost is expected to be fully amortized over the next three years, with $6 million and $3 million amortized during 2018 and 2019, respectively, with an immaterial amount amortized in 2020. Forfeitures are recorded as they occur. Our stock compensation costs may differ based on actual experience. The cost of stock compensation is included in the Consolidated Statements of Operations before, or in conjunction with, the vesting of options. Long Term Performance Plan Certain of our employees and directors participate in our Second Amended and Restated 2012 Long Term Performance Plan (the Amended 2012 LTPP), which includes awards originally granted under our 2012 Long Term Performance Plan and 2012 Directors Stock Incentive Plan. Restricted Stock Units: During the year ended December 31, 2017, we granted 220,194 RSUs to certain of our employees with a grant date fair value of $30.44 per unit, of which 775 RSUs cliff vest on the first anniversary of the grant date, 12,137 RSUs cliff vest on the second anniversary of the grant date and 207,282 RSUs vest ratably over a term of three years from the grant date. During the year ended December 31, 2017, we granted 29,431 RSUs to the independent directors with a grant date fair value of $28.25 per unit. These RSUs vest after one year from the grant date. The employee and director RSUs may be settled in cash or stock upon vesting at the sole discretion of the Compensation Committee. The table below presents a summary of our nonvested RSU awards activity for the year ended December 31, 2017. Number of Units Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 571 $ 20.57 Granted 250 30.19 Forfeited (167 ) 22.53 Vested (108 ) 22.76 Nonvested balance at December 31, 2017 546 $ 23.93 Director RSUs vested but not issued at December 31, 2017 63 $ 27.99 During the year ended December 31, 2017, 2016 and 2015, we granted restricted stock units with a weighted-average grant date fair value of $30.19, $18.92 and $32.12, respectively. Performance Units: During the year ended December 31, 2017, we granted 189,351 performance units at target level of 100% (with the potential for the delivery of up to 568,053 shares of our common stock at the maximum performance level) to certain of our employees with a grant date fair value of $30.54 per unit. Performance units cliff vest after three years based on our performance at the end of a three-year period beginning January 1, 2017. The number of shares of our common stock that are ultimately vested and delivered in respect of these performance units will range from 0% to 300% of the target grant amount. The vesting of performance units depends on the Company's performance, as approved by the Compensation Committee of our Board of Directors (the Compensation Committee), based on two metrics: book-to-bill and adjusted operating cash flow, each as measured over a three year performance period, and subject to adjustments based on the Company’s compounded annual growth rate for revenue over the same period. The performance units may be settled in cash or stock at the sole discretion of the Compensation Committee. The table below presents a summary of our nonvested performance share awards as of December 31, 2017. Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 554 $ 22.86 Granted 189 30.54 Forfeited (201 ) 24.90 Vested (33 ) 28.07 Nonvested balance at December 31, 2017 509 24.58 During the year ended December 31, 2017, 2016 and 2015, we granted performance units with a weighted-average grant date fair value of $30.54, $19.33 and $32.29, respectively. Performance Retention Awards: Performance retention awards were granted to certain of our executives with a grant date fair value of $32.82 in 2015. The performance retention awards cliff vest after three years based on our performance at the end of a three-year period ended December 31, 2017. The number of shares of our common stock that ultimately vested and delivered in respect of these performance retention awards was 50% of the target grant amount based on the Company’s performance against a metric of net debt to adjusted EBITDA, measured as of December 31, 2017. The performance retention awards may be settled in cash or stock at the sole discretion of the Compensation Committee. The table below presents a summary of our nonvested performance retention awards as of December 31, 2017. Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 99 $ 32.82 Granted — — Forfeited (20 ) 32.82 Vested (20 ) 32.82 Nonvested balance at December 31, 2017 59 $ 32.82 Effect of TASC Acquisition on Engility Equity Awards The TASC acquisition constituted a change of control under the grant agreements for Engility's outstanding RSUs, stock options, and performance shares. The impact on these equity grants was as follows: RSUs: Pursuant to the terms of the RSU grant agreements, 364,983 RSUs held by our employees vested. Certain executive officers waived vesting with respect to 229,166 RSUs and our independent directors waived vesting with respect to 11,790 RSUs. The TASC acquisition also triggered the issuance of shares for 43,950 vested RSUs held by the independent directors, pursuant to the terms of the grant agreements for these RSUs. Stock Options: Pursuant to the terms of the stock option grant agreements entered into with holders of outstanding stock options, the exercise price adjusted to reflect the Cash Dividend, provided, that to the extent that adjusting the exercise price by the full amount of the Cash Dividend resulted in the exercise price of the stock options falling below 25% of the fair market value of the shares underlying such stock options, such excess portion of the Cash Dividend was paid to holders of the affected stock options in cash. Performance Shares: Pursuant to the terms of the performance share agreements entered into with holders of outstanding performance shares, we fixed the number of underlying shares that are eligible to be vested and issued with respect to our outstanding grants of performance shares. For the performance shares granted in 2013, the number of eligible underlying shares was fixed at 127% of their target value based on Engility's performance against the financial metrics set forth in the grant agreements, measured as of a shortened performance period prior to the closing date of the TASC acquisition in accordance with the terms of the award agreements. For the performance shares granted in 2014, as less than half of the performance period was complete at the time of the closing of the TASC acquisition, the number of underlying shares was fixed at their target value of 100% in accordance with the terms of the award agreements. The performance shares cliff vest according to their grant agreement dates, three years from grant date. Employee Stock Purchase Plan On July 1, 2016, the shareholder-approved Employee Stock Purchase Plan (2016 ESPP) became effective. Under the 2016 ESPP, eligible employees are offered options to purchase shares of our common stock at the end of each six-month offering period at 90% of fair market value based on the closing market price for our stock on the purchase date. Eligible employees generally include all employees of Engility. The initial offering period commenced on July 1, 2016 and ended on December 31, 2016, and subsequent offering periods occur on the first trading day in January and July of each calendar year and end on the last trading day in June and December of each calendar year. Share purchases are funded through payroll deductions of up to 10% of an employee’s eligible compensation for each payroll period, or $25 each calendar year. For the initial offering period and the year ended December 31, 2016, 32,848 shares were purchased by employees at an average price of $30.50 per share. For the year ended December 31, 2017, 78,140 shares were purchased by employees for both offering periods at an average price of $25.34 per share.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Non-Cancellable Operating Leases We lease certain facilities and equipment under agreements expiring at various dates through 2027. Certain leases contain renewal options or escalation clauses providing for increased rental payments based upon maintenance, utility and tax increases. No lease agreement imposes a restriction on our ability to pay dividends, engage in debt or equity financing transactions, or enter into further lease agreements. The following table presents future minimum base rent payments under non-cancellable operating leases with initial terms in excess of one year at December 31, 2017. Real Estate Equipment Total 2018 $ 20,829 $ 127 $ 20,956 2019 17,177 99 17,276 2020 15,139 19 15,158 2021 13,688 — 13,688 2022 10,085 — 10,085 Thereafter 25,310 — 25,310 Total minimum payments required 102,228 245 102,473 Less: Sublease rentals under non-cancellable leases (58 ) — (58 ) Net minimum payments required $ 102,170 $ 245 $ 102,415 The following table presents rent expense under non-cancellable operating leases. Year Ended December 31, 2017 2016 2015 Rent expense $ 31,778 $ 38,945 $ 53,912 Letters of Credit We enter into standby letters of credit with financial institutions covering performance and financial guarantees pursuant to contractual arrangements with certain vendors and customers. We had total outstanding letters of credit aggregating $2 million at December 31, 2017. These letters of credit may be drawn upon in the event of our nonperformance. The letters of credit reduce the borrowing capacity of our revolving line of credit dollar-for-dollar. Procurement Regulations A substantial majority of our revenue is generated from providing services and products under legally binding agreements or contracts with U.S. government and foreign government customers. U.S. government contracts are subject to extensive legal and regulatory requirements, and from time to time, agencies of the U.S. government investigate whether such contracts were and are being conducted in accordance with these requirements. Currently we are cooperating with the U.S. government on several investigations from which civil or administrative proceedings have or could result and give rise to fines, penalties, compensatory and treble damages, restitution and/or forfeitures. Currently, we do not anticipate that any of these investigations will have a material adverse effect, individually or in the aggregate, on our consolidated financial position, results of operations or cash flows. However, under U.S. government regulations, our indictment by a Federal grand jury, or an administrative finding against us as to our present responsibility to be a U.S. government contractor or subcontractor, could result in our being suspended for a period of time from eligibility for awards of new government contracts or task orders or in a loss of export privileges. A conviction, or an administrative finding against us that satisfies the requisite level of seriousness, could result in debarment from contracting with the U.S. government for a specified term. In addition, all of our U.S. government contracts: (1) are subject to audit and various pricing and cost controls, (2) include standard provisions for termination for the convenience of the U.S. government or for default, and (3) are subject to cancellation if funds for contracts become unavailable. Foreign government contracts generally include comparable provisions relating to terminations for convenience and default, as well as other procurement clauses relevant to the foreign government. Litigation Matters We are also subject to litigation, proceedings, claims or assessments and various contingent liabilities incidental to our businesses. Furthermore, in connection with certain business acquisitions, we have assumed some or all claims against, and liabilities of, such acquired businesses, including both asserted and unasserted claims and liabilities. In accordance with the accounting standard for contingencies, we record a liability when management believes that it is both probable that a liability has been incurred and we can reasonably estimate the amount of the loss. Generally, the loss is recorded at the amount we expect to resolve the liability. The estimated amounts of liabilities recorded for pending and threatened litigation are recorded in other current liabilities in the Consolidated Balance Sheets. Amounts recoverable from insurance contracts or third parties are recorded as assets when deemed probable. At December 31, 2017 and 2016, we did not record any amounts for recoveries from insurance contracts or third parties in connection with the amount of liabilities recorded for pending and threatened litigation. Legal defense costs are expensed as incurred. We believe that we have recorded adequate provisions for our litigation matters. We review these provisions quarterly and adjusts these provisions to reflect the impact of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter. Although we believe that we have valid defenses with respect to legal matters and investigations pending against us, the results of litigation can be difficult to predict, particularly those involving jury trials. Accordingly, our current judgment as to the likelihood of our loss (or our current estimate as to the potential range of loss, if applicable) with respect to any particular litigation matter may turn out to be wrong. Therefore, it is possible that our financial position, results of operations or cash flows could be materially adversely affected in any particular period by the unfavorable resolution of one or more of these or other contingencies.

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2017
Postemployment Benefits [Abstract]
Employee Benefits	10. Employee Benefits Engility Employee Savings Plan. Under the Engility Master Savings Plan (the Engility Savings Plan), participating employees are eligible to receive Company matching or other contributions, in the form of cash effective January 1, 2015 or in the form of Engility common stock or cash in prior years, up to designated levels. For the year ended December 31, 2017, the plan provided a Company matching contribution for 50% of the first 8% of the employee contribution, for a maximum Company contribution of 4.0% of compensation. For the year ended December 31, 2016, the plan provided a Company matching contribution for 100% of the first 3% of the employee contribution and 50% of the next 3% of the employee contribution. The Company contributions under the Engility Savings Plan were $22 million, $26 million and $4 million for the years ended December 31, 2017, 2016 and 2015, respectively. TASC Defined Contribution Plan. Effective January 1, 2016, the TASC defined contribution plan (the TASC Savings Plan) was merged into the Engility Savings Plan. Upon the closing of the TASC acquisition, we assumed TASC's defined contribution plan in which substantially all TASC employees were eligible to participate. The TASC Savings Plan provided for a Company matching contribution for 100% of the first 3% of the employee contribution and an additional 50% of the next 2% of the employee contribution. Certain employees received matching contributions at a lower percentage based on their specific matching formula. Employee and employer contributions to the plan were made each pay period and are immediately vested. The Company’s total TASC Savings Plan contributions were $14 million for the period February 26, 2015, the date of the TASC acquisition, to December 31, 2015. TASC Defined Benefit Plan. Upon the closing of the TASC acquisition, we assumed TASC's defined benefit plan (the TASC benefit plan) in which certain employees are eligible to participate based upon service with TASC's prior parent. This plan offers two retirement programs, a Retiree Health Reimbursement Account Plan (RHRA) and a Cash Bonus Plan, which provide a restoration of certain pension benefits that would have been forfeited as a result of years of service and final average pay being frozen by TASC's prior parent. In December of 2015, payments of $3 million were made to participants in the Cash Bonus Plan and the plan was then terminated. DRC Defined Benefit Pension Plan. DRC's Defined Benefit Pension Plan (the DRC Pension Plan) is non-contributory, covering substantially all employees of DRC who had completed a year of service prior to July 1, 2002. Membership in the DRC Pension Plan was frozen effective July 1, 2002 and participants’ calculated pension benefit was frozen effective December 31, 2006. In the fourth quarter of 2015, the Company offered certain former employees who had vested benefits in the DRC Pension Plan the option of receiving a one-time lump sum payment equal to the present value of the participant’s pension benefit (payable in cash or rolled over into a qualified retirement plan or IRA). In December 2015, payments of $17 million were made from the plan to participants accepting the lump-sum offer. The Company recorded a pre-tax non-cash settlement charge of $3 million in 2015 as a result of these transactions. Our funding policy is to contribute at least the minimum amount required by the Employee Retirement Income Security Act of 1974. Additional amounts are contributed to assure that plan assets will be adequate to provide retirement benefits. No mandatory contributions are required to fund the DRC Pension Plan during 2018. Net Periodic Pension Cost DRC Pension Plan TASC Benefit Plan Year Ended December 31, Year Ended December 31, 2017 2016 2015 2017 2016 2015 (1) Service cost $ 823 $ 805 $ — $ — $ — $ — Interest cost on projected benefit obligations 2,499 2,543 3,997 495 468 470 Expected return on plan assets (3,817 ) (3,813 ) (5,833 ) — — — Net loss (gain) amortization 451 292 231 (72 ) — — Settlement loss — — 3,141 — — — Immediate recognition of benefit cost due to plan termination — — — — — 285 Net periodic benefit income (expense) $ (44 ) $ (173 ) $ 1,536 $ 423 $ 468 $ 755 (1) For the period from February 26, 2015 to December 31, 2015. Obligations and Funded Status DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 77,732 $ 78,665 $ 16,455 $ 18,146 Service cost 823 805 — — Interest cost 2,499 2,543 495 468 Benefits paid (4,508 ) (4,915 ) (333 ) (286 ) Actuarial loss (gain) 1,336 1,506 (272 ) (1,873 ) Administrative expenses paid (867 ) (872 ) — — Benefit obligation at end of year 77,015 77,732 16,345 16,455 Change in plan assets: Fair value of plan assets at beginning of year 48,489 50,130 — — Actual return on plan assets 5,547 3,286 — — Employer contributions 5,748 860 333 286 Benefits paid (4,508 ) (4,915 ) (333 ) (286 ) Administrative expenses paid (867 ) (872 ) — — Fair value of plan assets at end of year 54,409 48,489 — — Unfunded status $ (22,606 ) $ (29,243 ) $ (16,345 ) $ (16,455 ) Amounts recognized in the consolidated balance sheets consist of: DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Other current liabilities $ — $ — $ 811 $ 714 Other long-term liabilities 22,606 29,243 15,534 15,741 Net amount recognized $ 22,606 $ 29,243 $ 16,345 $ 16,455 The combined projected benefit obligation for the DRC Pension Plan and TASC Benefit Plan was $93 million and $94 million at December 31, 2017 and 2016, respectively. The reconciliation of the accumulated other comprehensive loss (gain) was as follows: DRC Pension Plan Beginning Balance Net Loss Amortization Experience Loss (Gain) Ending Balance 2017 $ 15,976 $ (451 ) $ (394 ) $ 15,131 2016 $ 14,235 $ (292 ) $ 2,033 $ 15,976 2015 $ 14,800 $ (291 ) $ (274 ) $ 14,235 TASC Benefit Plan Beginning Balance Net Gain Amortization Experience Gain Ending Balance 2017 $ (2,077 ) $ 72 $ (271 ) $ (2,276 ) 2016 $ (204 ) $ — $ (1,873 ) $ (2,077 ) 2015 $ — $ — $ (204 ) $ (204 ) The amounts recognized in other comprehensive loss are reflected, net of related tax effects, as a component of accumulated other comprehensive loss as part of stockholders’ equity in the accompanying consolidated Balance Sheets. The Company expects the amortization expense related to the net actuarial loss to be immaterial in 2018. Assumptions Beginning in 2016, we refined the method used to measure interest costs for pension and postretirement benefits. Previously, the cost was determined using a single weighted-average discount rate derived from the yield curve. Under the refined method, known as the spot rate approach, we use individual spot rates along the yield curve that correspond with the timing of each benefit payment. We believe this change provides a more precise measurement of interest costs by improving the correlation between projected cash outflows and corresponding spot rates on the yield curve. Compared to the previous method, the spot rate approach decreased the interest components of our benefit costs slightly in 2016 and 2017. There is no impact on the total benefit obligation. We accounted for this change prospectively as a change in accounting estimate. The discount rates represents the estimated rate at which we could effectively settle our pension benefit obligations. In order to estimate this rate for the DRC Pension Plan and the TASC Benefit Plan in 2017 and 2016, the timing of each benefit payment was matched against the individual spot rates along the Towers Watson RATE:Link yield curve to produce a single discount rate. During 2015, future expected cash flows of the plan were matched against the Towers Watson RATE:Link yield curve to produce a single discount rate. The assumed long-term rate of return on plan assets, which is the average return expected on the funds invested or to be invested to provide future benefits to pension plan participants, is determined by an annual review of historical plan assets returns and consultation with outside investment advisors. In selecting the expected long-term rate of return on assets used for the DRC Pension Plan, the Company considered its investment return goals stated in the Pension Plan’s investment policy. The Company, with input from the Pension Plan’s professional investment managers, also considered the average rate of earnings expected on the funds invested or to be invested to provide Pension Plan benefits. This process included determining expected returns for the various asset classes that comprise the Pension Plan’s target asset allocation. The following assumptions were used to determine the benefit obligations and net periodic benefit costs: Used to determine benefit obligations: DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Discount rate 3.53 % 3.95 % 3.33 % 3.54 % Rate of compensation increase N/A N/A N/A N/A Used to determine net periodic benefit costs: DRC Pension Plan TASC Benefit Plan Year Ended December 31, Year Ended December 31, 2017 2016 2015 2017 2016 2015 Discount rate 3.31 % 3.39 % 3.94 % (1) 3.08 % 2.85 % 3.05 % (2) Expected rate of return on assets 7.86 % 8.00 % 8.00 % N/A N/A N/A Rate of compensation increase N/A N/A N/A N/A N/A N/A (1) The discount rate used for the determination of the settlement in 2015 was 4.17%. (2) Represents the discounts rate for the RHRA Plan. The discount rate for the Cash Bonus Plan in 2015 was 0.95%. DRC Pension Plan Assets The Company’s investment policy includes a periodic review of the DRC Pension Plan’s investment in the various asset classes. During 2017, the Company’s overall investment strategy for plan assets was to achieve a long-term rate of return of 7.50%, with a wide diversification of asset types, fund strategies and fund managers. The target allocation ranges for the plan assets are 45% to 65% in equity securities; 30% to 50% in fixed income securities; 0% to 20% in other types of investments and 2% to 10% in cash and cash equivalents. The risk management practices include regular evaluations of fund managers to ensure the risk assumed is commensurate with the given investment style and objectives. Prohibited investments include, but are not limited to, margin transactions. According to the plan’s investment policy, the aggregate holdings of Company common stock may not exceed 3% of the total fund. Plan assets did not include any Company securities at both December 31, 2017 and 2016. The fair value measurement of plan assets by asset category at December 31, 2017 is as follows: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Asset Category Total (Level 1) (Level 2) (Level 3) Equity mutual funds $ 50,733 $ 50,733 $ — $ — Guaranteed deposit account 2,578 — — 2,578 Hedge funds 1,098 — — 1,098 Total $ 54,409 $ 50,733 $ — $ 3,676 The fair value measurement of plan assets by asset category at December 31, 2016 is as follows: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Asset Category Total (Level 1) (Level 2) (Level 3) Cash $ 301 $ 301 $ — $ — Money market funds 1,653 — 1,653 — Equity securities: Common equity securities 7,340 7,340 — — Equity mutual funds 86 86 — — Real estate investment trusts 43 43 — — Exchanged traded funds equity 17,542 17,542 — — Corporate and foreign bonds 15,101 — 15,101 — Hedge funds 6,423 — — 6,423 Total $ 48,489 $ 25,312 $ 16,754 $ 6,423 Fair Value Measurement Using Significant Unobservable Inputs (Level 3) A reconciliation of the beginning and ending balances of hedge fund assets is as follows: Guaranteed Deposit Account Hedge Funds Total Balance at December 31, 2015 $ — $ 6,438 $ 6,438 Actual returns on plan assets related to assets still held at the reporting date — 325 325 Purchases — 104 104 Sales — (444 ) (444 ) Balance at December 31, 2016 — 6,423 6,423 Actual returns on plan assets related to assets still held at the reporting date — 123 123 Purchases 2,578 — 2,578 Sales — (5,448 ) (5,448 ) Balance at December 31, 2017 $ 2,578 $ 1,098 $ 3,676 The Company’s hedge fund assets consists of interests in one hedge fund at December 31, 2017. The hedge fund is a multi-strategy equity hedge fund with a focus on investment strategies that exploit market inefficiencies to produce absolute returns with low correlation to global capital markets. The fair value of the hedge fund was estimated based on the investments net asset value at the reporting period as the fair value is not readily determinable and the investment fund meets the criteria of an investment company. Redemptions of the interests in the fund can be made quarterly based on the discretion of the investment company’s Board of Directors. During 2017, a second hedge fund was sold which was a fund of funds that combined diversified multi-strategy methods to achieve investment objectives during a three to five year investment cycle. Strategy methods may have consisted of conventional long-term equity and fixed income investments or derivative investments, including, total return swaps, options and forwards. The Guaranteed Deposit Account (GDA) is designed to provide liquidity and safety of principal with a competitive guaranteed rate of return. The fair value of the GDA approximates the market value of underlying investments by discounting expected future investment cash flow from both investment income and repayment of principal for each investment purchased directly for the defined benefit segment of the General Account. Principal and accumulated interest are fully guaranteed by Prudential Retirement Insurance and Annuity Company (PRIAC). The declared interest rate is announced each year in advance and is determined by PRIAC. The GDA invests in a broadly diversified, fixed-income portfolio within PRIAC’s general account. The portfolio is invested in public bonds, commercial mortgages and private placement bonds. As of December 31, 2017, the average credit quality of the portfolio was AA- and the average duration was 3.7 years. Estimated Future Benefit Payments The following table sets forth the expected timing of benefit payments by fiscal year: DRC Pension Plan TASC Benefit Plan Total 2018 $ 4,966 $ 811 $ 5,777 2019 $ 4,996 $ 874 $ 5,870 2020 $ 5,064 $ 1,052 $ 6,116 2021 $ 5,038 $ 1,263 $ 6,301 2022 $ 5,037 $ 1,420 $ 6,457 Five subsequent fiscal years $ 24,620 $ 7,690 $ 32,310

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	11. Debt 2016 Credit Facility On August 12, 2016, the Company and Engility Corporation entered into a credit agreement (the 2016 Credit Facility) with the lenders and issuing banks from time to time party thereto and Morgan Stanley Senior Funding, Inc., as administrative agent (Morgan Stanley). On August 14, 2017 (the Second Amendment Effective Date), the Company and Engility Corporation (the Borrower) entered into Amendment No. 2 (the Second Amendment) to the Credit Agreement, dated as of August 12, 2016, and amended by Amendment No. 1 thereto, dated as of February 13, 2017, by and among the Borrower, the Company, the several lenders from time to time parties thereto and Morgan Stanley Senior Funding, Inc., as administrative agent and collateral agent. The parties entered into the Second Amendment in order to reduce the interest rate applicable to (i) the Borrower’s senior secured term B1 loan facility in the original principal amount of $195 million (Existing Term B1 Loans) from 2.25% to 1.75%, in the case of alternate base rate loans, and from 3.25% to 2.75%, in the case of Eurocurrency loans, and (ii) the Borrower’s senior secured term B2 loan facility in the original principal amount of $608 million (Existing Term B2 Loans) from 2.75% to 2.25%, in the case of alternate base rate loans, and from 3.75% to 3.25%, in the case of Eurocurrency loans. The Second Amendment was accomplished by (i) the Borrower obtaining new term B1 loan commitments (Term B1 Loans) to refinance the Existing Term B1 Loans and Morgan Stanley making additional Term B1 Loans to the Borrower in a principal amount equal to $185 million minus the principal amount of any Existing Term B1 Loans outstanding on the Second Amendment Effective Date that were converted into Term B1 Loans on the Second Amendment Effective Date, and (ii) the Borrower obtaining new term B2 loan commitments (Term B2 Loans) to refinance the Existing Term B2 Loans and Morgan Stanley making additional Term B2 Loans to the Borrower in a principal amount equal to $579 million minus the principal amount of any Existing Term B2 Loans outstanding on the Second Amendment Effective Date that were converted into Term B2 Loans on the Second Amendment Effective Date. The proceeds of the Term B1 Loans and Term B2 Loans, respectively, will be applied to repay in full the Existing Term B1 Loans and Existing Term B2 Loans, respectively, outstanding as of the Second Amendment Effective Date. On February 13, 2017 (the First Amendment Effective Date), the Company and Engility Corporation (the Borrower) entered into Amendment No. 1 (the First Amendment) to the Credit Agreement, dated as of August 12, 2016 (the 2016 Credit Facility), among the Borrower, the Company, the several lenders from time to time parties thereto and Morgan Stanley, as administrative agent and collateral agent. The parties entered into the First Amendment in order to reduce the interest rate applicable to (i) the Borrower’s senior secured term B1 loan facility in the original principal amount of $200 million (Existing Term B1 Loans) from 3.25% to 2.25%, in the case of alternate base rate loans, and from 4.25% to 3.25%, in the case of Eurocurrency loans, and (ii) the Borrower’s senior secured term B2 loan facility in the original principal amount of $680 million (Existing Term B2 Loans) from 3.75% to 2.75%, in the case of alternate base rate loans, and from 4.75% to 3.75%, in the case of Eurocurrency loans. The First Amendment was accomplished by (i) the Borrower obtaining new term B1 loan commitments (New Term B1 Loans) to reprice the Existing Term B1 Loans and Morgan Stanley making additional New Term B1 Loans to the Borrower in a principal amount equal to $195 million minus the principal amount of any Existing Term B1 Loans outstanding on the First Amendment Effective Date that were converted into New Term B1 Loans on the First Amendment Effective Date, and (ii) the Borrower obtaining new term B2 loan commitments (New Term B2 Loans) to reprice the Existing Term B2 Loans and Morgan Stanley making additional New Term B2 Loans to the Borrower in a principal amount equal to $608 million minus the principal amount of any Existing Term B2 Loans outstanding on the First Amendment Effective Date that were converted into New Term B2 Loans on the First Amendment Effective Date. The proceeds of the New Term B1 Loans and New Term B2 Loans, respectively, were applied to repay in full the Existing Term B1 Loans and Existing Term B2 Loans, respectively, outstanding as of the First Amendment Effective Date. The 2016 Credit Facility provides for aggregate commitments of $1,045 million, consisting of (a) a $200 million senior secured term B1 loan facility (Term B1 Loan), (b) a $680 million senior secured term B2 loan facility (Term B2 Loan; the Term B1 Loan and the Term B2 Loan collectively are referred to as the Term Loans), and (c) a $165 million senior secured revolving credit facility (Revolver). The Revolver includes subfacilities for the issuance of letters of credit in an aggregate face amount of up to $35 million and a swingline commitment for swingline borrowings of up to $35 million at any time outstanding. The Term B1 Loan and the Term B2 Loan were fully drawn on August 12, 2016. The 2016 Credit Facility provides that Engility Corporation has the right to seek commitments to provide additional term loan facilities or additional revolving credit commitments in an aggregate principal amount up to the sum of (x) $150.0 million plus (y) an additional amount so long as, after giving pro forma effect to the incurrence of such additional borrowings, Engility Corporation’s first lien secured leverage ratio would be equal to or less than 4.00:1.00, subject to certain conditions and receipt of commitments by existing or additional lenders. The lenders under the 2016 Credit Facility are not under any obligation to provide any such additional term loan facilities or revolving credit commitments. The proceeds of the Term Loans, together with proceeds from the offering of the Notes (as defined below), were used by Engility Corporation to (i) prepay all existing indebtedness outstanding under the first lien credit agreement dated May 23, 2014, as amended, and the second lien credit agreement dated May 23, 2014, as amended, each among Engility Corporation, the lenders and issuing banks from time to time party thereto, and Barclays Bank PLC as administrative agent and collateral agent (the 2015 Credit Facilities), (ii) to pay transaction costs associated with the foregoing and (iii) for general corporate purposes. The proceeds of future borrowings under the Revolver may be used for general corporate purposes. Borrowings under the 2016 Credit Facility bear interest at a rate per annum equal to, at Engility Corporation’s option, either (a) a base rate determined by reference to the higher of (1) the interest rate announced from time to time by Morgan Stanley as its prime rate, (2) the Federal funds effective rate plus 0.5% and (3) LIBOR determined by reference to the costs of funds for U.S. dollar deposits for a one-month interest period plus 1%, subject to statutory reserves and (x) in the case of the Term B2 Loan, a floor of 1% and (y) in the case of the Term B1 Loan and Revolver, a floor of 0%, or (b) LIBOR determined by reference to the costs of funds for U.S. dollar deposits for the interest period relevant to such borrowing, subject to statutory reserves and (x) in the case of the Term B2 Loan, a floor of 1% and (y) in the case of the Term B1 Loan and Revolver, a floor of 0%, and in the case of either (a) or (b), plus an applicable margin. In addition to paying interest on outstanding principal under the Revolver, Engility Corporation is required to pay a commitment fee of 0.50% in respect of the unutilized commitments thereunder, payable quarterly in arrears. Engility Corporation can voluntarily reduce the unutilized portion of the commitment amount and repay outstanding loans under the 2016 Credit Facility at any time without premium or penalty, other than customary “breakage” costs with respect to LIBOR loans and a 1.00% premium if certain repricing transactions are consummated within the first six months after the borrowings of the Term Loans. The Term B1 Loan will mature on August 12, 2020 and will require scheduled quarterly payments in an amount equal to 2.50% of the original principal amount thereof, commencing December 31, 2016, with the balance paid at maturity. The Term B2 Loan will mature on August 12, 2023 and will require scheduled quarterly payments in amounts equal to 0.25% of the original principal amount thereof, commencing December 31, 2016, with the balance paid at maturity. The Revolver will mature on August 12, 2021. No amortization will be required with respect to the Revolver. In addition, the 2016 Credit Facility requires Engility Corporation to prepay outstanding Term Loans, subject to certain exceptions, with: • 50% (which percentage will be reduced to 25% if the Company’s net first lien secured leverage ratio is not greater than 3.50:1.00 and to 0% if the Company’s net first lien secured leverage ratio is not greater than 3.00:1.00) of Engility Corporation’s annual excess cash flow (as defined by the 2016 Credit Facility); • 100% of the net cash proceeds of all non-ordinary course asset sales or other non-ordinary course dispositions of property or certain casualty events, in each case subject to certain exceptions and provided that Engility Corporation may (a) reinvest within 450 days or (b) commit to reinvest those proceeds within 450 days and so reinvest such proceeds within 630 days in assets to be used in its business, or certain other permitted investments; and • 100% of the net cash proceeds of any issuance or incurrence of debt, other than proceeds from debt permitted under the 2016 Credit Facility. All obligations under the 2016 Credit Facility are unconditionally guaranteed by the Company and each of the Company’s existing and future direct and indirect material, wholly owned domestic restricted subsidiaries, subject to certain exceptions, pursuant to that certain Guarantee and Collateral Agreement, dated as of August 12, 2016, made by the Company, Engility Corporation and each of the subsidiary guarantors party thereto in favor of Morgan Stanley as collateral agent for the banks and other financial institutions or entities from time to time party to the 2016 Credit Facility (the Guarantee and Collateral Agreement). The obligations are secured by first-priority security interests in substantially all tangible and intangible assets of the Company, Engility Corporation and each subsidiary guarantor, in each case whether owned on the date of the initial borrowings or thereafter acquired. The 2016 Credit Facility requires Engility Corporation to maintain compliance with a maximum ratio of consolidated first lien secured debt to consolidated EBITDA (the consolidated first lien net leverage ratio) of 6.125 to 1.00, with incremental step downs over time, and places certain restrictions on the ability of the Company, Engility Corporation and their restricted subsidiaries to, among other things, incur debt and liens; merge, consolidate or liquidate; dispose of assets; enter into hedging arrangements; pay dividends and make other restricted payments; undertake transactions with affiliates; enter into restrictive agreements on dividends and other distributions; make negative pledges; enter into sale-leaseback transactions; make certain investments; prepay or modify the terms of certain indebtedness; and modify the terms of certain organizational agreements. We believe our most restrictive covenant is the consolidated first lien net leverage ratio requirement in the 2016 Credit Facility, which as of December 31, 2017 was 3.25:1.00. The consolidated first lien net leverage ratio is the ratio of (a) (i) funded debt secured by liens as of such date minus (ii) the unrestricted cash as of such date to (b) consolidated bank EBITDA for the period of the four fiscal quarters most recently ended. As of December 31, 2017, we were in compliance with all covenants under the 2016 Credit Facility. The 2016 Credit Facility contains customary events of default, including payment defaults, breaches of representations and warranties, covenant defaults, cross-defaults to other material indebtedness, certain events of bankruptcy and insolvency, material judgments, certain ERISA events, invalidity of loan documents and certain changes in control. Indenture and Senior Notes On August 12, 2016, the Company, Engility Corporation and certain of the Company’s wholly owned domestic subsidiaries named as guarantors (each such subsidiary and the Company individually, a Guarantor and collectively, the Guarantors) entered into an indenture with Deutsche Bank Trust Company Americas, as trustee, (the Indenture), pursuant to which Engility Corporation issued $300 million aggregate principal amount of 8.875% Senior Notes due 2024 (the Notes) and the Guarantors provided guarantees of the Notes (each individually, a Guarantee and collectively, the Guarantees). The Notes are general senior unsecured obligations of Engility Corporation, ranking equal in right of payment with Engility Corporation’s existing and future senior indebtedness and senior in right of payment of any of Engility Corporation’s future subordinated indebtedness. The Notes are effectively junior to any future or existing secured indebtedness of the Company and Engility Corporation, including indebtedness under the 2016 Credit Facility, to the extent of the value of the assets securing such indebtedness. The Notes are structurally subordinated to all existing and future indebtedness and other obligations of Engility Corporation’s subsidiaries that do not guarantee the Notes. The Guarantee of the Notes by each Guarantor is: (i) a general senior obligation of such Guarantor; (ii) equal in right of payment to all existing and future indebtedness of such Guarantor that is not subordinated in right of payment to its Guarantee of the Notes (including its guarantee of the 2016 Credit Facility); (iii) effectively subordinated to any existing and future indebtedness of such Guarantor that is secured with property or assets of such Guarantor to the extent of the value of such property and assets securing such indebtedness (including the 2016 Credit Facility); and (iv) senior in right of payment to any future indebtedness of such Guarantor that is expressly subordinated in right of payment of the Notes. Interest on the Notes is payable on March 1 and September 1 of each year, beginning on March 1, 2017, with the Notes maturing on September 1, 2024. Engility Corporation may redeem the Notes before September 1, 2019, in whole or in part, at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest, if any, to, but not including, the redemption date plus an applicable make-whole premium. The Notes are redeemable, in whole or part, at any time on or after September 1, 2019 at the redemption prices (expressed as percentages of the principal amount thereof) set forth below, plus accrued and unpaid interest thereon, if any, to, but not including, the applicable redemption date, if redeemed during the 12-month period beginning on September 1 of each of the years indicated below: Year Percentage 2019 104.438 2020 102.219 2021 and thereafter 100.000 In addition, until September 1, 2019, Engility Corporation the Company may redeem up to 35% of the Notes with cash proceeds of certain equity offerings at a redemption price equal to 108.875% of the principal amount of the Notes plus accrued and unpaid interest, if any, to, but not including, the applicable redemption date. However, Engility Corporation may only make such redemptions if at least 60% of the aggregate principal amount of the Notes issued under the Indenture remains outstanding immediately after the occurrence of such redemption and that such redemption occurs within 120 days of the closing date of such equity offering. In the event of a change of control (as defined in the Indenture) of Engility Corporation, Engility Corporation will be required to offer to purchase the Notes at 101% of their face amount, plus accrued and unpaid interest up to, but not including, the repurchase date. The terms of the Indenture restrict the ability of Engility Corporation and certain of its subsidiaries to borrow money, create liens on assets, make distributions and pay dividends on or redeem or repurchase stock, make certain types of investments, sell stock in certain subsidiaries, enter into agreements that restrict dividends or other payments from subsidiaries, enter into transactions with affiliates, issue guarantees of debt, and sell assets or merge with other companies. These limitations are subject to a number of important exceptions and qualifications set forth in the Indenture. The Indenture provides for customary events of default which include (subject in certain cases to grace and cure periods), among others: nonpayment of principal or interest or premium, breach of covenants or other agreements in the Indenture, default for failure to pay certain other indebtedness, the failure to pay certain final judgments, and certain events of bankruptcy, insolvency or reorganization. Generally, if an event of default occurs and is continuing under the Indenture, either the trustee or the holders of at least 30% in aggregate principal amount of the Notes then outstanding may declare the principal amount plus accrued and unpaid interest on the Notes to be immediately due and payable. 2015 Credit Facilities On August 12, 2016, in connection with the effectiveness of the 2016 Credit Facility, as described above, the Company terminated its 2015 Credit Facilities. The 2015 Credit Facilities consisted of: (i) an $830 million senior secured first lien term loan facility, (ii) a $115 million senior secured revolving credit facility and (iii) a $400 million senior secured second lien term loan facility. In connection with the acquisition of TASC, which included the payment of the Cash Dividend and the repayment of outstanding debt under the 2013 Credit Facility (as defined below), we borrowed $585 million under a promissory note issued by our wholly-owned subsidiary Engility LLC (f/k/a Engility Corporation) and guaranteed by Predecessor Engility (as defined below) and certain other Predecessor Engility subsidiaries (the Engility Bridge Loan). In addition, we guaranteed the debt of TASC comprised of the First Lien Credit Agreement and the Second Lien Credit Agreement, consisting of (a)(i) a $395 million senior secured first lien term loan facility (the Original First Lien Term Facility), (ii) a $50 million senior secured revolving credit facility and (iii) a $250 million senior secured second lien term loan facility (the Original Second Lien Term Facility) (the existing facilities in clauses (a)(i) through (a)(iii), collectively, the TASC Existing Credit Facilities) and (b)(i) a new $435 million senior secured first lien term loan facility (the Incremental First Lien Term Facility), (ii) additional senior secured first lien revolving credit capacity in an aggregate principal amount of $65 million and (iii) a new $150 million senior secured second lien term loan facility (the Incremental Second Lien Term Facility) (the incremental facilities in clauses (b)(i) through (iii), collectively, the TASC Incremental Facilities and along with the TASC Existing Credit Facilities, the 2015 Credit Facility), in each case with Barclays Bank PLC as administrative agent. All borrowings under the 2015 Credit Facility pursuant to the First Lien Credit Agreement bore interest at a variable rate per annum equal to an applicable margin, plus, at our option (other than for swing line loans), either (1) a base rate determined by reference to the highest of (a) the prime rate of Barclays Bank PLC, (b) the Federal funds effective rate plus 0.50% and (c) a LIBOR rate determined by reference to the cost of funds for U.S. dollar deposits for the interest period of one month, plus 1.00% or (2) a LIBOR rate determined by reference to the costs of funds for U.S. dollar deposits for the interest period relevant to such borrowing, provided that for the Original First Lien Term Facility and Incremental First Lien Term Facility, the LIBOR rate shall not be less than 1.00%. All swing line loans bore interest at a variable rate per annum equal to an applicable margin, plus a base rate determined as described in the immediately preceding sentence. The applicable LIBOR margin and the applicable base rate margin for borrowings under the First Lien Credit Agreement were 6.00% and 5.00%, respectively. All borrowings under the 2015 Credit Facility pursuant to the Second Lien Credit Agreement bore interest at a rate per annum equal to 12.00%. Debt Summary The composition of our debt at December 31, 2017 and 2016 was as follows: December 31, 2017 2016 Term Loans $ 713,000 $ 823,300 Notes 300,000 300,000 Other 314 461 Total debt 1,013,314 1,123,761 Less: current portion of long-term debt (26,947 ) (26,947 ) Less: unamortized original issue discount costs and financing fees (47,680 ) (56,821 ) Long-term debt $ 938,687 $ 1,039,993 During 2017, we repaid a total of $110 million of debt under the 2016 Credit Facility, which included the prepayment of $83 million. We incurred approximately $3 million in fees related to the repricing of term loan debt in 2017. Our availability under the Revolver of the 2016 Credit Facility was $163 million as of December 31, 2017, with $2 million outstanding under letters of credit. During 2016, in connection with the termination of the 2015 Credit Facilities, the Company incurred a $10 million early termination penalty under the Second Lien Credit Agreement. The Company also expensed $5 million of deferred debt issuance costs associated with the 2015 Credit Facilities in 2016. In addition, the Company expensed approximately $11 million of debt issuances costs related to the 2016 Credit Facility and Notes that did not qualify for deferral. During 2015, in connection with the TASC Incremental Facilities, the Company expensed $5 million of deferred debt issuance costs associated with the 2013 Credit Facility. Furthermore, the Company expensed debt issuance costs of approximately $1 million that did not qualify for deferral. These amounts are reflected in interest expense, net in the Consolidated Statements of Operations. During the year ended December 31, 2017, we had a weighted average outstanding loan balance of $1,073 million, which accrued interest at a weighted average borrowing rate of approximately 5.91%. Our weighted average outstanding loan balance for the year ended December 31, 2016 was $1,147 million, which accrued interest at a weighted average borrowing rate of approximately 8.07%. Our weighted average outstanding loan balance for the year ended December 31, 2015 was $1,077 million, which accrued interest at a weighted average borrowing rate of approximately 8.22%. The following table presents our minimum debt principal payments. Minimum Debt Principal Payments 2018 $ 26,947 2019 26,967 2020 141,800 2021 6,800 2022 6,800 Thereafter 804,000 Total minimum payments required $ 1,013,314

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	12. Fair Value Measurements Derivative Instruments During 2017, the Company entered into an interest rate swap agreement for contracts with an initial notional amount of $281 million. These contracts become effective December 29, 2017 and expire on December 31, 2020. The other terms of these instruments are as follows: Contract received: Floating interest rate LIBOR (subject to minimum of 1.00%) Contract paid: Fixed interest rates 1.947% - 1.949% Assets and Liabilities Measured at Fair Value on a Recurring Basis The following table presents our assets and liabilities that are measured at fair value on a recurring basis: December 31, December 31, Balance Sheet Classification Fair Value Hierarchy 2017 2016 Interest rate swap assets Other assets Level 2 $ 1,129 $ — Interest rate swap liabilities Other current liabilities Level 2 $ (477 ) $ — The Company’s interest rate swap assets and liabilities were measured at fair value on a recurring basis and were aggregated by the level in the fair value hierarchy within which those measurements fall. All instruments were classified as Level 2 and there were no transfers of financial instruments between the three levels of fair value hierarchy during the periods the interest rate swap agreements were in effect. During 2016, the Company terminated its interest rate swap agreements related to the 2015 Credit Facility which resulted in a $2 million termination charge and a loss of approximately $1 million. The derivative instruments were comprised of a combined notional amount of $200 million effective December 31, 2015 which would have expired December 31, 2016. The other terms of these instruments were as follows: Contract received: Floating interest rate LIBOR (subject to minimum of 1.25%) Contract paid: Fixed interest rates 3.09% - 3.18%

Restructuring and Integration C

Restructuring and Integration Costs	12 Months Ended
	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Restructuring and Integration Costs	13. Restructuring and Integration Costs During 2017, we incurred $2 million in lease termination fees which were paid out by the end of 2017. During 2016, we incurred $12 million in restructuring costs, including severance which were paid out during 2017, and other costs to include lease termination fees which were paid out by the end of 2016. During 2015, in conjunction with the integration of TASC, we incurred $21 million in restructuring costs, including costs related to workforce reduction which were paid out during 2016, and other costs to include contract and lease termination fees which were paid out during 2017. The activity and balance of the liability accounts are as follows: Severance and Related Costs Other Restructuring Costs Total Balance as of December 31, 2014 $ 368 $ 6,036 $ 6,404 Additions 14,614 6,476 21,090 Cash payments (10,976 ) (3,041 ) (14,017 ) Balance as of December 31, 2015 4,006 9,471 13,477 Additions 9,357 2,186 11,543 Cash payments (12,059 ) (6,704 ) (18,763 ) Other adjustments — (2,429 ) (2,429 ) Balance as of December 31, 2016 1,304 2,524 3,828 Additions — 1,859 1,859 Cash payments (1,304 ) (3,479 ) (4,783 ) Other adjustments — (904 ) (904 ) Balance as of December 31, 2017 $ — $ — $ — Restructuring and severance-related costs are contained within the selling, general and administrative expense line in the accompanying consolidated statement of operations. The restructuring liabilities were recognized within other current liabilities in the accompanying consolidated balance sheets.

Separate Financial Information

Separate Financial Information of Subsidiary Guarantor of Indebtedness	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Separate Financial Information of Subsidiary Guarantor of Indebtedness	14. Separate Financial Information of Subsidiary Guarantor of Indebtedness The following tables present supplemental condensed consolidating financial statements of (a) Engility Holdings, Inc., as parent company guarantor, (b) Engility Corporation, as subsidiary issuer of the Notes; (c) on a combined basis, the subsidiary guarantors of the Notes; and (d) on a combined basis, the subsidiaries that are not guarantors of the Notes. Separate financial statements of the subsidiary guarantors are not presented because the parent company owns 100% of the outstanding voting stock of each of the subsidiary guarantors and the guarantee by each subsidiary guarantor is joint and several and full and unconditional, except for certain customary limitations. These customary limitations, which are described in detail in the Indenture, include (i) the sale, exchange or transfer of a guarantor, (ii) the guarantor ceasing to guarantee the 2016 Credit Facility, (iii) the designation of a guarantor as a unrestricted subsidiary (iv) exercising the legal defeasance, covenant defeasance or discharge of the Indenture, and (v) the merger or consolidation of a guarantor with the issuer or another guarantor of the Indenture. In accordance with Rule 3-10(d) of Regulation S-X under the Securities Exchange Act of 1934, as amended, the Company includes the following tables in these notes to the condensed consolidated financial statements. SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 31,966 $ 36 $ 9,888 $ — $ 41,890 Receivables, net — 301,047 9,562 20,485 — 331,094 Intercompany receivables — — 28,069 7,738 (35,807 ) — Other current assets — 17,300 (4 ) 2,385 — 19,681 Total current assets — 350,313 37,663 40,496 (35,807 ) 392,665 Property, plant and equipment, net — 43,933 — 73 — 44,006 Goodwill — 1,071,371 — — — 1,071,371 Identifiable intangible assets, net — 361,410 — — — 361,410 Deferred tax assets — 150,535 — — — 150,535 Investment in subsidiaries 676,105 67,623 31,876 — (775,604 ) — Other assets — 5,976 45 — — 6,021 Total assets $ 676,105 $ 2,051,161 $ 69,584 $ 40,569 $ (811,411 ) $ 2,026,008 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 52,826 — 128 — 52,954 Intercompany payable — 35,807 — — (35,807 ) — Accrued employment costs — 68,622 1,961 6,962 — 77,545 Accrued expenses — 74,657 — 199 — 74,856 Advance payments and billings in excess of costs incurred — 30,380 — — — 30,380 Income tax liabilities — 320 — 228 548 Other current liabilities — 25,512 — 1,176 26,688 Total current liabilities — 315,071 1,961 8,693 (35,807 ) 289,918 Long-term debt — 938,687 — — — 938,687 Income tax liabilities — 62,219 — — — 62,219 Other liabilities — 59,079 — — — 59,079 Total liabilities — 1,375,056 1,961 8,693 (35,807 ) 1,349,903 Shareholders' equity 676,105 676,105 67,623 31,876 (775,604 ) 676,105 Total liabilities and equity $ 676,105 $ 2,051,161 $ 69,584 $ 40,569 $ (811,411 ) $ 2,026,008 SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 31,144 $ 365 $ 16,727 $ — $ 48,236 Receivables, net — 297,334 18,030 18,884 — 334,248 Intercompany receivables — 124,741 — 758 (125,499 ) — Assets held for sale, current — 2,332 17,910 — — 20,242 Other current assets — 27,437 506 2,461 — 30,404 Total current assets — 482,988 36,811 38,830 (125,499 ) 433,130 Property, plant and equipment, net — 46,413 3 131 — 46,547 Goodwill — 1,078,454 — — — 1,078,454 Identifiable intangible assets, net — 393,891 — — — 393,891 Deferred tax assets — 236,457 (4,174 ) — — 232,283 Assets held for sale — 1 11,961 — — 11,962 Investment in subsidiaries 704,805 (60,902 ) 29,248 — (673,151 ) — Other assets — 2,292 — — — 2,292 Total assets $ 704,805 $ 2,179,594 $ 73,849 $ 38,961 $ (798,650 ) $ 2,198,559 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 43,848 37 58 — 43,943 Intercompany payable — 758 124,741 — (125,499 ) — Accrued employment costs — 87,263 4,466 7,131 — 98,860 Accrued expenses — 76,520 — 350 — 76,870 Advance payments and billings in excess of costs incurred — 33,259 — — — 33,259 Income tax liabilities — — — 230 (21 ) 209 Liabilities held for sale, current — — 4,341 — — 4,341 Other current liabilities — 34,398 47 1,944 21 36,410 Total current liabilities — 302,993 133,632 9,713 (125,499 ) 320,839 Long-term debt — 1,039,993 — — — 1,039,993 Income tax liabilities — 64,852 — — — 64,852 Liabilities held for sale — — 1,084 — — 1,084 Other liabilities — 66,951 35 — — 66,986 Total liabilities — 1,474,789 134,751 9,713 (125,499 ) 1,493,754 Shareholders' equity 704,805 704,805 (60,902 ) 29,248 (673,151 ) 704,805 Total liabilities and equity $ 704,805 $ 2,179,594 $ 73,849 $ 38,961 $ (798,650 ) $ 2,198,559 SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,755,936 $ 32,519 $ 143,432 $ — $ 1,931,887 Costs and expenses Cost of revenue — 1,470,400 56,340 128,989 — 1,655,729 Selling, general and administrative expenses — 134,670 3,287 4,434 — 142,391 Goodwill impairment — 7,083 — — — 7,083 Total costs and expenses — 1,612,153 59,627 133,423 — 1,805,203 Operating income (loss) — 143,783 (27,108 ) 10,009 — 126,684 Interest expense, net — 76,716 — — — 76,716 Other expenses (income), net — (17 ) (4 ) 248 — 227 Income (loss) in equity investments in subsidiaries (35,191 ) (21,920 ) 5,185 — 51,926 — Income (loss) before income taxes (35,191 ) 45,164 (21,919 ) 9,761 51,926 49,741 Provision for income taxes — 80,355 1 — — 80,356 Net income (loss) (35,191 ) (35,191 ) (21,920 ) 9,761 51,926 (30,615 ) Less: Net income attributable to non-controlling interest — — — 4,576 — 4,576 Net income (loss) attributable to Engility $ (35,191 ) $ (35,191 ) $ (21,920 ) $ 5,185 $ 51,926 $ (35,191 ) Net income (loss) $ (35,191 ) $ (35,191 ) $ (21,920 ) $ 9,761 $ 51,926 $ (30,615 ) Other comprehensive income — 1,060 — — — 1,060 Comprehensive income (loss) (35,191 ) (34,131 ) (21,920 ) 9,761 51,926 (29,555 ) Less: Net income attributable to non-controlling interest — — — 4,576 — 4,576 Comprehensive income (loss) attributable to Engility $ (35,191 ) $ (34,131 ) $ (21,920 ) $ 5,185 $ 51,926 $ (34,131 ) SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE LOSS FOR THE YEAR ENDED DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,834,718 $ 87,539 $ 154,166 $ — $ 2,076,423 Costs and expenses Cost of revenue — 1,503,356 133,307 141,181 — 1,777,844 Selling, general and administrative expenses — 145,215 17,964 3,059 — 166,238 Goodwill impairment — 9,875 — — — 9,875 Total costs and expenses — 1,658,446 151,271 144,240 — 1,953,957 Operating income (loss) — 176,272 (63,732 ) 9,926 — 122,466 Interest expense, net — 131,185 — — — 131,185 Other expenses (income), net — (135 ) 1 214 — 80 Income (loss) in equity investments in subsidiaries (10,807 ) (58,753 ) 4,974 — 64,586 — Income (loss) before income taxes (10,807 ) (13,531 ) (58,759 ) 9,712 64,586 (8,799 ) Provision (benefit) for income taxes — (2,724 ) (6 ) — — (2,730 ) Net income (loss) (10,807 ) (10,807 ) (58,753 ) 9,712 64,586 (6,069 ) Less: Net income attributable to non-controlling interest — — — 4,738 — 4,738 Net income (loss) attributable to Engility $ (10,807 ) $ (10,807 ) $ (58,753 ) $ 4,974 $ 64,586 $ (10,807 ) Net income (loss) $ (10,807 ) $ (10,807 ) $ (58,753 ) $ 9,712 $ 64,586 $ (6,069 ) Other comprehensive income — 2,364 — — — 2,364 Comprehensive income (loss) (10,807 ) (8,443 ) (58,753 ) 9,712 64,586 (3,705 ) Less: Net income attributable to non-controlling interest — — — 4,738 — 4,738 Comprehensive income (loss) attributable to Engility $ (10,807 ) $ (8,443 ) $ (58,753 ) $ 4,974 $ 64,586 $ (8,443 ) SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME FOR THE YEAR ENDED DECEMBER 31, 2015 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,796,441 $ 151,514 $ 156,704 $ (19,036 ) $ 2,085,623 Costs and expenses Cost of revenue — 1,519,802 135,985 142,958 (19,036 ) 1,779,709 Selling, general and administrative expenses 184,397 15,162 3,703 — 203,262 Goodwill impairment — 292,100 — — — 292,100 Total costs and expenses — 1,996,299 151,147 146,661 (19,036 ) 2,275,071 Operating income (loss) — (199,858 ) 367 10,043 — (189,448 ) Interest expense (income), net — 110,148 — (5 ) — 110,143 Other expense (income), net — (1,289 ) 4 — — (1,285 ) Income (loss) in equity investments in subsidiaries (235,352 ) 3,018 4,935 — 227,399 — Income (loss) before income taxes (235,352 ) (305,699 ) 5,298 10,048 227,399 (298,306 ) Benefit for income taxes — (70,347 ) 2,280 — — (68,067 ) Net income (loss) (235,352 ) (235,352 ) 3,018 10,048 227,399 (230,239 ) Less: Net income attributable to non-controlling interest — — — 5,113 — 5,113 Net income (loss) attributable to Engility $ (235,352 ) $ (235,352 ) $ 3,018 $ 4,935 $ 227,399 $ (235,352 ) Net income (loss) $ (235,352 ) $ (235,352 ) $ 3,018 $ 10,048 $ 227,399 $ (230,239 ) Other comprehensive income — 1,789 — — — 1,789 Comprehensive income (loss) (235,352 ) (233,563 ) 3,018 10,048 227,399 (228,450 ) Less: Net income attributable to non-controlling interest — — — 5,113 — 5,113 Comprehensive income (loss) attributable to Engility $ (235,352 ) $ (233,563 ) $ 3,018 $ 4,935 $ 227,399 $ (233,563 ) SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ (62,082 ) $ 152,481 $ 7,274 $ — $ 97,673 Investing activities: Proceeds from sale of business, net of amount placed in escrow — 22,349 — — — 22,349 Proceeds from sale of property, plant and equipment — 2,902 — — — 2,902 Capital expenditures — (9,691 ) — — — (9,691 ) Net cash provided by investing activities — 15,560 — — — 15,560 Financing activities: Repayment of long-term debt — (110,447 ) — — — (110,447 ) Gross borrowings from revolving credit facility — 318,500 — — — 318,500 Repayments of revolving credit facility — (318,500 ) — — — (318,500 ) Payment of employee withholding taxes on share-based compensation (1,501 ) — — — — (1,501 ) Dividends paid (407 ) — — — — (407 ) Distributions to non-controlling interest member — — — (7,133 ) — (7,133 ) Due (to) from subsidiaries 1,908 157,882 (152,810 ) (6,980 ) — — Net cash provided by (used in) financing activities — 47,435 (152,810 ) (14,113 ) — (119,488 ) Change in cash from assets held from sale — (91 ) — — — (91 ) Net change in cash and cash equivalents — 822 (329 ) (6,839 ) — (6,346 ) Cash and cash equivalents, beginning of period — 31,144 365 16,727 — 48,236 Cash and cash equivalents, end of period $ — $ 31,966 $ 36 $ 9,888 $ — $ 41,890 SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ 163,949 $ (82,167 ) $ 12,623 $ — $ 94,405 Investing activities: Capital expenditures — (21,446 ) — — — (21,446 ) Net cash used in investing activities — (21,446 ) — — — (21,446 ) Financing activities: Gross borrowings from issuance of long-term debt — 1,180,000 — — — 1,180,000 Repayment of long-term debt — (1,215,754 ) — — — (1,215,754 ) Gross borrowings from revolving credit facility — 137,000 — — — 137,000 Repayments of revolving credit facility — (137,000 ) — — — (137,000 ) Debt issuance costs — (9,988 ) — — — (9,988 ) Proceeds from share-based payment arrangements 214 — — — — 214 Payment of employee withholding taxes on share-based compensation (1,779 ) — — — — (1,779 ) Dividends paid (1,709 ) — — — — (1,709 ) Distributions to non-controlling interest member — — — (3,865 ) — (3,865 ) Due (to) from subsidiaries 3,274 (82,066 ) 82,503 (3,711 ) — — Net cash provided by (used in) financing activities — (127,808 ) 82,503 (7,576 ) — (52,881 ) Change in cash from assets held from sale — (1,864 ) — — — (1,864 ) Net change in cash and cash equivalents — 12,831 336 5,047 — 18,214 Cash and cash equivalents, beginning of period — 18,313 29 11,680 — 30,022 Cash and cash equivalents, end of period $ — $ 31,144 $ 365 $ 16,727 $ — $ 48,236 SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2015 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by operating activities $ 5,530 $ 85,842 $ (50,963 ) $ 13,539 $ — $ 53,948 Investing activities: Acquisitions, net of cash acquired — 25,478 — — — 25,478 Capital expenditures — (19,610 ) — — — (19,610 ) Net cash used in investing activities — 5,868 — — — 5,868 Financing activities: Gross borrowings from issuance of long-term debt — 585,000 — — — 585,000 Repayment of long-term debt — (403,674 ) — — — (403,674 ) Gross borrowings from revolving credit facility — 157,000 — — — 157,000 Repayments of revolving credit facility — (115,000 ) — — — (115,000 ) Debt issuance costs — (42,425 ) — — — (42,425 ) Equity issuance costs (2,590 ) — — — — (2,590 ) Proceeds from share-based payment arrangements 279 — — — — 279 Payment of employee withholding taxes on share-based compensation (8,021 ) — — — — (8,021 ) Dividends paid (204,304 ) — — — — (204,304 ) Distributions to non-controlling interest member — — — (3,182 ) — (3,182 ) Due (to) from subsidiaries 209,106 (254,298 ) 47,865 (2,673 ) — — Net cash provided by financing activities (5,530 ) (73,397 ) 47,865 (5,855 ) — (36,917 ) Net change in cash and cash equivalents — 18,313 (3,098 ) 7,684 — 22,899 Cash and cash equivalents, beginning of period — — 3,127 3,996 — 7,123 Cash and cash equivalents, end of period $ — $ 18,313 $ 29 $ 11,680 $ — $ 30,022

Basis of Presentation (Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	Description of Business: Engility Holdings, Inc. (Engility) has provided mission critical services to the U.S. government for more than 60 years. Engility offers a broad range of highly technical services, leveraging our strengths in systems engineering, cybersecurity, high performance computing, enterprise modernization, and training and mission operations to solve our customers’ most difficult challenges. Engility has a diversified portfolio that serves the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and space-related and intelligence community agencies, including the Central Intelligence Agency (CIA), the National Security Agency (NSA), the National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), National Aeronautical and Space Administration (NASA) and U.S Air Force Space Command (AFSPC). As used herein, the terms “Engility,” the “Company,” “we,” “us” or “our” refers to (i) Engility and its subsidiaries, for all periods prior to the closing of the TASC, Inc. (TASC) acquisition, and (ii) New Engility and its subsidiaries, for all periods following the TASC acquisition. The TASC acquisition was effected through a new holding company named New East Holdings, Inc. (New Engility). As a result of the business combination, New Engility succeeded to and continues to operate, directly or indirectly, the existing business of Engility and, indirectly, acquired the existing business of TASC. As of December 31, 2017, we employed approximately 8,700 individuals globally and operated in 44 countries. Engility has no operations other than owning 100% of the capital stock of Engility Corporation (formerly TASC, Inc.), a Massachusetts corporation (Engility Corporation), and the consolidated financial statements of Engility and its consolidated subsidiaries are identical in all respects to the consolidated financial statements of Engility Corporation and its consolidated subsidiaries. On July 17, 2012, L3 Technologies, Inc. completed the spin-off of Engility Holdings, Inc. from L3. Unless the context indicates otherwise, (i) references to Engility, the Company, we, us or our refer to Engility Holdings, Inc. and its subsidiaries and (ii) references to L3 refer to L3 Communications Holdings and its subsidiaries.
Principles of Consolidation and Combination and Basis of Presentation	Principles of Consolidation and Combination and Basis of Presentation: The Consolidated Financial Statements are prepared in conformity with accounting principles generally accepted in the United States of America (U.S. GAAP) and reflect the financial position, results of operations and cash flows of Engility as a separate standalone entity. The Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. On January 31, 2014 and February 26, 2015, we completed the acquisitions of Dynamics Research Corporation (DRC) and TASC, respectively, which are more fully described in Note 3. These transactions were recorded using the purchase method of accounting; accordingly, DRC's and TASC's financial results are included in the Consolidated Financial Statements for the periods subsequent to the acquisition.
Non-controlling Interest	Non-controlling Interest: Engility holds a 50.1% majority interest in Forfeiture Support Associates J.V. (FSA). The results of operations of FSA are included in Engility’s Consolidated Statements of Operations. The non-controlling interest reported on the Consolidated Balance Sheets represents the portion of FSA’s equity that is attributable to the non-controlling interest.
Accounting Estimates	Accounting Estimates: The preparation of financial statements in conformity with GAAP requires management to make estimates using assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. The most significant of these estimates relate to revenue recognition, recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income taxes, pension and defined benefit plan obligations and contingencies. Actual results experienced by the Company may differ materially from management's estimates.
Out-of-period adjustments	Out-of-period adjustments: During 2016, the Company recorded out-of-period adjustments that decreased pre-tax income by $2 million to correct errors related to the year ended December 31, 2015. The adjustments were not material to 2016 or any previously issued financial statements.
Revenue Recognition	Revenue Recognition: Substantially all of the Company’s revenue is derived from services provided to the U.S. government and its agencies, primarily by the Company’s consulting staff and, to a lesser extent, subcontractors. The Company generates its revenue from the following types of contractual arrangements: cost-reimbursable-plus-fee contracts, time-and-materials contracts, and fixed-price contracts. Revenue on cost-reimbursable-plus-fee contracts is recognized as services are performed, generally based on allowable costs plus any recognizable earned fee. The Company considers fixed fees under cost-reimbursable-plus-fee contracts to be earned in proportion to the allowable costs incurred in performance of the contract. For cost-reimbursable-plus-fee contracts that include performance-based fee incentives, which are principally award fee arrangements, revenue and profit on award fees are recognized as work on the contracts is performed. We have significant history with the client for the majority of these contracts, and that history and management’s evaluation and monitoring of performance form the basis of estimated fees recorded. Estimates of the total fee to be earned are made based on contract provisions, prior experience with similar contracts or clients, and management’s evaluation of the performance on such contracts. Revenue for time-and-materials contracts is recognized as services are performed, generally on the basis of contract allowable labor hours worked multiplied by the contract-defined billing rates, plus allowable direct costs and indirect cost allocations associated with materials used and other direct expenses incurred in connection with the performance of the contract. Revenue on fixed-price contracts is recognized using a percentage-of-completion method based on actual costs incurred relative to total estimated costs for the contract. These estimated costs are updated during the term of the contract, and may result in revision by the Company of recognized revenue and estimated costs in the period in which they are identified by cumulative catch-up adjustments. Profits on fixed-price contracts result from the difference between incurred costs and revenue earned. Percentage-of-completion contract accounting requires significant judgment relative to assessing risks, estimating contract revenue and costs, and making assumptions for schedule and technical issues. Due to the size and nature of many of our contracts, developing total revenue and cost at completion estimates require the use of significant judgment. Contract costs include direct labor and billable expenses, an allocation of allowable indirect costs, and warranty obligations. Billable expenses are comprised of subcontracting costs and other direct costs that often include, but are not limited to, travel-related costs and telecommunications charges. We recognize revenue and billable expenses from these transactions on a gross basis. Assumptions regarding the length of time to complete the contract also include expected increases in wages and prices for materials. Estimates of total contract revenue and costs are monitored during the term of the contract and are subject to revision as the contract progresses. Anticipated losses on contracts are recognized in the period they are deemed probable and can be reasonably estimated. Anticipated contract losses recorded for both of the years ended December 31, 2017 and 2016 were $1 million and for the year ended December 31, 2015 were $2 million. For the year ended December 31, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $12 million, of which $3 million was directly related to favorable performance on contracts with award fees. Amounts related to changes in estimates at completion for the year ended December 31, 2016 represented a net increase to revenue and operating income of $18 million, of which $4 million was directly related to favorable performance on contracts with award fees. The Company’s contracts may include the delivery of a combination of one or more of the Company’s service offerings. In these situations, the Company determines whether such arrangements with multiple service offerings should be treated as separate units of accounting based on how the elements are bid or negotiated, whether the customer can accept separate elements of the arrangement, and the relationship between the pricing on the elements individually and combined. Included in unbilled receivables, a component of receivables, net, are certain restructuring costs related to the performance of our U.S. government contracts which are required to be recorded under GAAP but are not currently allocable to contracts. Such costs are expensed outside of our indirect rates and recognized as revenue for the portion we expect to be recoverable in our rates. At both December 31, 2017 and 2016 these receivables were approximately $9 million and $11 million, respectively, and are allocated to contracts when they are paid or otherwise agreed. We regularly assess the probability of recovery of these costs. This assessment requires us to make assumptions about the extent of cost recovery under our contracts and the amount of future contract activity. If the level of backlog in the future does not support the continued expensing of these costs, the profitability of our remaining contracts could be adversely affected. Revenue and profit in connection with contracts to provide services to the U.S. government that contain collection risk because the contracts are incrementally funded and subject to the availability of funds appropriated are deferred until a contract modification is obtained, indicating that adequate funds are available to the contract or task order.
Cost of Revenue	Cost of Revenue: Cost of revenue primarily consists of compensation expenses for program personnel, the fringe benefits associated with this compensation, other direct expenses incurred to complete programs, including cost of materials and subcontract efforts.
Selling, General, and Administrative Expenses	Selling, General, and Administrative Expenses: Selling, general and administrative expenses are expensed as incurred.
Share-Based Compensation	Share-Based Compensation: Certain key employees of Engility participate in share-based compensation plans. We follow the fair value based method of accounting for share-based employee compensation, which requires us to expense all share-based employee compensation. We issue performance shares and restricted stock units (RSUs) under our existing plans to employees of the Company. Compensation expense is recognized for the entire award, net of estimated forfeitures, on a straight line basis over the requisite service period, which is generally three years, based on the grant date fair value.
Income Taxes	Income Taxes: We account for income taxes using the asset and liability method. Under this method, deferred tax assets and liabilities are recorded for the future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect of a tax rate change on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. On December 22, 2017, the President of the United States signed into law the Tax Cuts and Jobs Act (the “Tax Act”). Further information on the tax impacts of the Tax Reform Act is included in Note 7 of the Company’s consolidated financial statements. In evaluating our ability to recover our deferred tax assets, in full or in part, we consider all available positive and negative evidence, including our past operating results, and our forecast of future earnings, future taxable income and prudent and feasible tax planning strategies. The assumptions utilized in determining future taxable income require significant judgment and are consistent with the plans and estimates we are using to manage the underlying business. Actual operating results in future years could differ from our current assumptions, judgments and estimates. However, we believe that it is more likely than not that most of the deferred tax assets recorded on our Consolidated Balance Sheet will ultimately be realized. We record a valuation allowance to reduce our deferred tax assets to the net amount that we believe is more likely than not to be realized. At December 31, 2017 the valuation allowance of $1 million was related to a portion of state deferred tax assets, foreign tax credits and charitable donations that we are not expected to realize. At December 31, 2017 and 2016, we had long-term net deferred tax assets of $151 million and $232 million, respectively.
Cash and Cash Equivalents	Cash and Cash Equivalents: Cash and cash equivalents represent cash that is directly attributable to the Company. Cash equivalents consist of highly liquid investments with an original maturity of three months or less at the time of purchase.
Property, Plant and Equipment	Property, Plant and Equipment: Property, plant and equipment are stated at cost, less accumulated depreciation. Depreciation is computed by applying the straight-line method to the estimated useful lives of the related assets. Useful lives for buildings are 30 years. Useful lives for leasehold improvements and machinery, equipment, furniture and fixtures range from 3 to 10 years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the improvements. When property or equipment is retired or otherwise disposed of, the net book value of the asset is removed from our balance sheet and the net gain or loss is included in the determination of operating income. Maintenance and repairs are charged to expense as incurred.
Goodwill	Goodwill: We record goodwill in connection with the acquisition of businesses when the purchase price exceeds the fair values of the assets acquired and liabilities assumed. Generally, the largest intangible assets from the businesses that we acquire are the assembled workforces, which includes the human capital of the management, administrative, marketing and business development, engineering and technical employees of the acquired businesses. The success of our businesses, including our ability to retain existing business (revenue arrangements) and to compete successfully for and win new business (revenue arrangements), is primarily dependent on the management, marketing and business development, contracting, engineering and technical skills and knowledge of our employees, rather than on productive capital (plant and equipment, and technology and intellectual property). Additionally, for a significant portion of our businesses, our ability to attract and retain employees who have U.S. government security clearances, particularly those of top-secret and above, is critical to our success, and is often a prerequisite for retaining existing revenue arrangements and pursuing new ones. Therefore, because intangible assets for assembled workforces are part of goodwill in accordance with the accounting standards for business combinations, the substantial majority of the intangible assets for our business acquisitions are recognized as goodwill. Additionally, the value assigned to goodwill for our business acquisitions also includes the value that we expect to realize from cost reduction measures that we implement for our acquired businesses. The carrying value of goodwill is not amortized, but is tested for impairment annually as of November 30 as well as whenever events or changes in circumstances indicate that the carrying amount of a reporting unit may not be recoverable. A reporting unit is an operating segment, as defined by the segment reporting accounting standards, or a component of an operating segment. A component of an operating segment is a reporting unit if the component constitutes a business for which discrete financial information is available and is reviewed by operating segment management. The process of an impairment test is to identify any potential impairment by comparing the carrying value of a reporting unit including goodwill and its fair value. We determine the fair value of the reporting units using a hybrid method valuation approach which includes (1) the Income Approach (also referred to as a discounted cash flow or DCF), and (2) the Guideline Public Company Method. An impairment charge is recognized for the amount by which the carrying amount exceeds the reporting unit’s fair value, however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit.
Identifiable Intangible Assets	Identifiable Intangible Assets: As part of the accounting for our business acquisitions, identifiable intangible assets are recognized as assets if they arise from contractual or other legal rights, or if they are capable of being separated or divided from the acquired business and sold, transferred, licensed, rented or exchanged. We do not recognize any intangible assets apart from goodwill for the assembled workforces of our business acquisitions. Identifiable intangible assets include customer contractual relationships, contractual backlog and technology. The initial measurement of these intangible assets is based on their fair values. The most significant identifiable intangible asset that is separately recognized for our business acquisitions is customer contractual relationships. All of our customer relationships are established through written customer contracts (revenue arrangements). The fair value for customer contractual relationships is determined, as of the date of acquisition, based on estimates and judgments regarding expectations for the estimated future after-tax earnings and cash flows (including cash flows for working capital) arising from the follow-on revenue on contract (revenue arrangement) renewals expected from the customer contractual relationships over their estimated lives, including the probability of expected future contract renewals and revenue, less a contributory assets charge, all of which is discounted to present value. Identifiable intangible assets are: (1) tested for impairment whenever events or changes in circumstances indicate that the carrying amount of these assets may not be recoverable and (2) amortized over their estimated useful lives as the economic benefits are consumed, ranging from 1 to 20 years. We evaluate the carrying amount and the remaining useful lives of identifiable intangible assets on a quarterly basis at the asset group level. To the extent events or changes in circumstances indicate the carrying amount of these assets may not be recoverable, we test recoverability based on our projection of the undiscounted future operating cash flows of the related asset group. To the extent such projections indicate that future undiscounted cash flows are not sufficient to recover the carrying amount, we recognize a non-cash impairment charge to reduce the carrying amount to fair value. No impairment charges related to identifiable intangible assets were recorded in the three years ending December 31, 2017. To evaluate the reasonableness of the useful lives of the identifiable intangible assets on a quarterly basis, the Company considers whether there have been any significant changes to the nature of the customer contractual relationships, including customers served by Engility, contract types and nature of work performed, subsequent to the date the intangibles were acquired.
Assets and Liabilities Held for Sale	Assets and Liabilities Held for Sale: The Company entered into two separate agreements during the second half of 2016 to sell certain assets and liabilities owned by the Company both of which were completed in the first quarter of 2017. Depreciation for these assets ceased on the date they were designated as held for sale. The held for sale assets and liabilities were recorded at the lower of carrying value or estimated fair value, less an estimate of costs to sell. The estimate of fair value included unobservable inputs (Level 3 fair value). These assets and liabilities were designated as assets held for sale and liabilities held for sale in the accompanying consolidated balance sheets as of December 31, 2016. On January 6, 2017, the Company completed the sale of its international development services business, International Resources Group Ltd. (IRG), for an initial purchase price of $25 million in cash, subject to a cash on hand adjustment of $1 million finalized in the third quarter of 2017 and working capital adjustments that were finalized in January 2018 for approximately $2 million. As a result of the working capital adjustments, the Company recorded a loss of approximately $1 million at December 31, 2017. The sale was the result of the Company’s strategic review of its businesses and determination that the USAID portion of the Company’s international business no longer closely aligned with the Company’s future strategic direction. The Company used the proceeds from this sale, less an indemnity escrow of approximately $2 million, in the first quarter of 2017, to pay down existing debt. The Company expects to receive the indemnity escrow on or about the second anniversary of the sale assuming no claims are made against the escrow funds. In connection with the sale of IRG, and based on the final selling price of the business being less than carrying value of the assets as of December 31, 2016, the Company recorded a non-cash goodwill impairment charge of $10 million in 2016. During the first quarter of 2017, the Company completed its sale of long-term assets with carrying value totaling $2 million (net of accumulated depreciation of $1 million). The carrying amounts of assets and liabilities that were classified as held for sale were as follows: December 31, 2016 Assets held for sale, current: Cash and cash equivalents $ 1,864 Receivables, net 14,886 Other current assets 3,492 Assets held for sale, current $ 20,242 Assets held for sale: Property, plant and equipment, net $ 868 Goodwill 4,849 Identifiable intangible assets, net 6,245 Assets held for sale $ 11,962 Liabilities held for sale, current: Accounts payable, trade $ 727 Accrued expenses 3,268 Advance payments and billings in excess of costs incurred 271 Other current liabilities 75 Liabilities held for sale, current $ 4,341 Liabilities held for sale: Other liabilities $ 1,084 Liabilities held for sale $ 1,084
Pension and Defined Benefit Plans	Pension and Defined Benefit Plans: The Company measures plan assets and benefit obligations as of the date of its fiscal year end. Accounting and reporting for the Company's pension and defined benefit plans requires the use of assumptions, including but not limited to, a discount rate and an expected return on assets. These assumptions are reviewed at least annually based on reviews of current plan information and consultation with the Company's independent actuary and the plans’ investment advisor. If these assumptions differ materially from actual results, the Company's obligations under the pension and defined benefit plans could also differ materially, potentially requiring the Company to record an additional liability. The Company's pension and defined benefit plan liabilities are developed from actuarial valuations, which are performed each year.
Derivative Instruments	Derivative Instruments: The Company recognizes derivative instruments as either an asset or liability measured at its fair value. For derivative instruments that have been formally designated as a cash flow hedge, the effective portion of changes in the fair value of the derivative instruments are recorded in accumulated other comprehensive income (loss). Amounts in accumulated other comprehensive income (loss) are reclassified into earnings when interest expense on the underlying borrowings is recognized. The Company had entered into multiple interest rate swap contracts which reduced the exposure to variability in cash flows relating to interest payments on a portion of its outstanding debt payments. These interest rate contracts were designated as cash flow hedges. The effective portion of the derivative’s gain or loss was initially reported in accumulated other comprehensive income (loss) and would be subsequently reclassified into earnings in the same period or periods during which the hedged forecasted transaction affects earnings. The ineffective portion of the gain or loss of a cash flow hedge would be reported in earnings.
Fair Value Measurements	Fair Value Measurements: The Company utilizes fair value measurement guidance prescribed by GAAP to value its financial instruments. The guidance includes a definition of fair value, prescribes methods for measuring fair value, establishes a fair value hierarchy based on the inputs used to measure fair value and expands disclosures about the use of fair value measurements. Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. The carrying values of cash and cash equivalents, contract receivables and accounts payable approximate fair value because of the short-term nature of these instruments. The carrying value of the Term Loans, excluding original issue discount, and Notes approximated their fair value at December 31, 2017. The fair value of the Term Loans and Notes are based on quotes from a nationally recognized fixed income trading platform and is considered to be a Level 2 input, measured under GAAP hierarchy.
Earnings Per Share	Earnings per Share: Basic EPS is computed by dividing net income (loss) by the weighted average number of shares of common stock outstanding for the period. Diluted EPS reflects the weighted-average effect of all potentially dilutive securities outstanding during the periods. Diluted EPS includes the incremental effect of the employee stock purchase plan, restricted stock units, and stock options calculated using the treasury stock method. For the years ended December 31, 2017, 2016 and 2015, 532,060 shares, 766,935 shares and 570,181 shares, respectively, of common stock were not included in diluted EPS due to their anti-dilutive effects. The following table sets forth the reconciliation of the weighted average shares outstanding and calculation of EPS: Year Ended December 31, 2017 2016 2015 Net loss attributable to Engility $ (35,191 ) $ (10,807 ) $ (235,352 ) Weighted average number of shares outstanding – Basic 36,838 36,730 33,536 Dilutive effect of share-based compensation outstanding after application of the treasury stock method — — — Weighted average number of shares outstanding – Diluted 36,838 36,730 33,536 Loss per share attributable to Engility Basic $ (0.96 ) $ (0.29 ) $ (7.02 ) Diluted $ (0.96 ) $ (0.29 ) $ (7.02 )
New Accounting Pronouncements	New Accounting Pronouncements In September 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2017-13, Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842) In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In May 2017, the FASB issued ASU No. 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting In March 2017, the FASB issued ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The update requires employers to present the service cost component of the net periodic benefit cost in the same income statement line item as other employee compensation costs arising from services rendered during the period. The other components of net benefit cost, including interest cost, expected return on plan assets, amortization of prior service cost/credit and actuarial gain/loss, and settlement and curtailment effects, are to be presented outside of any subtotal of operating income. Employers will have to disclose the line(s) used to present the other components of net periodic benefit cost, if the components are not presented separately in the income statement. ASU 2017-07 is effective for fiscal years and interim periods beginning after December 15, 2017, and early adoption is permitted. The Company does not believe the adoption of this accounting standard will have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test of Goodwill Impairment, In November 2016, the FASB issued ASU No. 2016-18, Restricted Cash—a consensus of the FASB Emerging Issues Task Force In August 2016, the FASB issued Accounting Standards Update ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force) In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting. In February 2016, the FASB issued ASU No. 2016-02, Leases In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (ASC 606) Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross Versus Net) , Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing Revenue from Contracts with Customers (Topic 606): Narrow Scope Improvements and Practical Expedients; Revenue from Contracts with Customers (Topic 606): Technical Corrections and Improvements, Income Statement – Reporting Comprehensive Income (Topic 220), Revenue Recognition (Topic 605), and Revenue from Contracts with Customers (Topic 606). As the new standard impacts several of our business processes, systems and controls, the Company developed and implemented a comprehensive project plan to guide through the process of adopting the new standard. To assess the impact of adopting ASC 606, Engility reviewed its contract population by selecting samples upon which to perform detailed contract analyses. These contract analyses entailed reviewing each selected contract to determine the appropriate accounting treatment under ASC 606. These contract reviews were performed in a phased approach, enabling the Company to identify specific ASC 606-related risk areas for subsequent, more focused analyses. We will continue to recognize revenue and profit for the majority of our performance obligations over time as work is performed because the customer simultaneously receives and consumes the benefits provided by our performance and based upon the continuous transfer of control to the customer as costs are incurred. For U.S. government contracts, this continuous transfer of control to the customer is supported by clauses in the contract that allow the customer to unilaterally terminate the contract for convenience, pay us for costs incurred plus a reasonable profit and take control of any work in process. Engility management identified two primary areas likely to result in ASC 606-related impact: • Unfunded Performance Obligations - Revenue Recognition • Customized Products - Some of Engility’s contracts with customers entail building products to customer specifications. Under ASC 605, revenue for these customized products was recognized at the time of product delivery. Under ASC 606, the Company will change its revenue recognition methodology from point in time to over time for customized products, as they meet at least one of the overtime criteria. As Engility will adopt ASC 606 using the modified retrospective method, the Company must record a one-time cumulative impact of adoption at January 1, 2018. While we are still in the process of finalizing the impact of adoption, we currently estimate the cumulative impact will reduce accumulated deficit by less than $2 million, which management believes is not material.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Carrying Amounts of Assets and Liabilities Classified as Held for Sale	The carrying amounts of assets and liabilities that were classified as held for sale were as follows: December 31, 2016 Assets held for sale, current: Cash and cash equivalents $ 1,864 Receivables, net 14,886 Other current assets 3,492 Assets held for sale, current $ 20,242 Assets held for sale: Property, plant and equipment, net $ 868 Goodwill 4,849 Identifiable intangible assets, net 6,245 Assets held for sale $ 11,962 Liabilities held for sale, current: Accounts payable, trade $ 727 Accrued expenses 3,268 Advance payments and billings in excess of costs incurred 271 Other current liabilities 75 Liabilities held for sale, current $ 4,341 Liabilities held for sale: Other liabilities $ 1,084 Liabilities held for sale $ 1,084
Earnings Per Share	Year Ended December 31, 2017 2016 2015 Net loss attributable to Engility $ (35,191 ) $ (10,807 ) $ (235,352 ) Weighted average number of shares outstanding – Basic 36,838 36,730 33,536 Dilutive effect of share-based compensation outstanding after application of the treasury stock method — — — Weighted average number of shares outstanding – Diluted 36,838 36,730 33,536 Loss per share attributable to Engility Basic $ (0.96 ) $ (0.29 ) $ (7.02 ) Diluted $ (0.96 ) $ (0.29 ) $ (7.02 )

Business Acquisitions (Tables)

Business Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Summary of Allocation of Purchase Price	The final allocation of purchase price is as follows: Purchase Price Allocation Number of Engility shares issued 18,937,765 Share price on February 26, 2015 $ 46.45 Dividend payable to Engility stockholders 11.434 Value of Engility shares issued to TASC stockholders $ 35.016 Equity consideration $ 663,125 Cash $ 25,478 Receivables 149,041 Prepaid and deferred income taxes, current 26,015 Other current assets 26,286 Property, plant and equipment 15,835 Deferred tax assets 175,180 Other assets 5,096 Current portion of long-term debt (4,097 ) Accounts payable, trade (34,503 ) Accrued employment costs (92,396 ) Accrued expenses (33,387 ) Advance payments and billings in excess of costs incurred (18,004 ) Deferred income taxes, current and income taxes payable (248 ) Other current liabilities (32,522 ) Long-term debt (619,227 ) Other long-term liabilities (24,446 ) Identifiable intangible assets 358,300 Goodwill 740,724 $ 663,125
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The valuation of the identified intangible assets acquired is summarized below: Identifiable Intangible Assets Useful Life (years) Customer contractual relationships 15 $ 333,600 Contractual backlog 1 17,700 Technology 15 7,000 Total intangible assets $ 358,300
Business Acquisition Pro Forma Information	Revenue $ 2,239,577 Operating (loss) income $ (143,496 )

Receivables (Tables)

Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Components of Contract Receivables	The components of contract receivables are presented in the table below. December 31, 2017 2016 Billed receivables $ 119,506 $ 97,661 Unbilled receivables 222,994 248,253 Allowance for doubtful accounts (11,406 ) (11,666 ) Total receivables, net $ 331,094 $ 334,248
Allowance for Doubtful Accounts	The following table details the allowance for doubtful accounts: Year Ended December 31, 2017 2016 2015 Balance at beginning of year $ 11,666 $ 11,480 $ 1,482 Charged to expense 12 744 10,286 Deductions (272 ) (558 ) (288 ) Balance at end of year $ 11,406 $ 11,666 $ 11,480

Goodwill and Identifiable Int27

Goodwill and Identifiable Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amounts of goodwill were as follows: Goodwill Balance as of December 31, 2015 Goodwill $ 2,060,314 Accumulated impairment losses (967,136 ) 1,093,178 Impairment charge (9,875 ) Goodwill allocated to assets held for sale (4,849 ) Balance as of December 31, 2016 Goodwill 2,055,465 Accumulated impairment losses (977,011 ) 1,078,454 Impairment charge (7,083 ) Balance as of December 31, 2017 Goodwill 2,055,465 Accumulated impairment losses (984,094 ) $ 1,071,371 The amount of goodwill for each of our reporting units is shown in the following table: December 31, 2017 2016 Space Systems $ 367,526 $ 288,594 Intelligence Solutions 318,242 260,129 Defense 385,603 242,243 International — N/A Federal Civilian N/A 187,582 Products N/A 99,906 Total $ 1,071,371 $ 1,078,454
Information on Identifiable Intangible Assets	Information on our identifiable intangible assets that are subject to amortization is presented in the table below. December 31, 2017 December 31, 2016 Weighted Average Amortization Period Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount (in years) Customer contractual relationships 17 $ 545,229 $ 189,497 $ 355,732 $ 545,229 $ 157,482 $ 387,747 Technology 15 7,000 1,322 5,678 7,000 856 6,144 Total $ 552,229 $ 190,819 $ 361,410 $ 552,229 $ 158,338 $ 393,891
Amortization Expense Recorded for Identifiable Intangible Assets	Our recorded amortization expense for our identifiable intangible assets is presented in the table below. Year Ended December 31, 2017 2016 2015 Amortization expense $ 32,481 $ 36,491 $ 45,222
Estimated Amortization Expense for Identifiable Intangible Assets	Based on gross carrying amounts at December 31, 2017, our estimate of amortization expense for identifiable intangible assets are presented in the table below. Year Ended December 31, 2018 2019 2020 2021 2022 Amortization expense $ 32,482 $ 32,482 $ 32,482 $ 32,482 $ 32,482

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Schedule of Property, Plant and Equipment	The components of property, plant and equipment are presented in the table below. December 31, 2017 2016 Land $ 900 $ 900 Buildings and improvements 850 850 Machinery, equipment, furniture and fixtures 31,208 28,622 Leasehold improvements 41,757 43,598 Assets under construction 3,606 1,861 Gross property, plant and equipment 78,321 75,831 Accumulated depreciation and amortization (34,315 ) (29,284 ) Property, plant and equipment, net $ 44,006 $ 46,547
Schedule of Depreciation Expense	Our recorded depreciation expense for property, plant and equipment assets is presented in the table below. Year Ended December 31, 2017 2016 2015 Depreciation expense $ 12,091 $ 10,306 $ 13,213

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income from Continuing Operations before Income Taxes	Income (loss) before income taxes is summarized in the table below. Year Ended December 31, 2017 2016 2015 Domestic $ 49,114 $ (9,285 ) $ (298,644 ) Foreign 627 486 338 Income before income taxes $ 49,741 $ (8,799 ) $ (298,306 )
Components of Current and Deferred Portions of Provision for Income Taxes from Continuing Operations	The components of our current and deferred portions of the provision for income taxes are presented in the table below. Year Ended December 31, 2017 2016 2015 Current income tax provision (benefit): Federal $ (2,678 ) $ (4,030 ) $ (29,632 ) State and local 301 107 (1,569 ) Foreign 105 (14 ) 727 Subtotal (2,272 ) (3,937 ) (30,474 ) Deferred income tax provision (benefit): Federal 84,464 2,252 (31,830 ) State and local (1,836 ) (1,089 ) (5,718 ) Foreign — 44 (45 ) Subtotal 82,628 1,207 (37,593 ) Total provision (benefit) for income taxes $ 80,356 $ (2,730 ) $ (68,067 )
Schedule of Effective Income Tax Rate Reconciliation from Continuing Operations	A reconciliation of the statutory Federal income tax rate to our effective income tax rate is presented in the table below. Year Ended December 31, 2017 2016 2015 Statutory Federal income tax rate 35.0 % 35.0 % 35.0 % State and local income taxes, net of Federal income tax benefit 3.0 6.6 1.7 Goodwill impairment 5.0 (33.2 ) (18.0 ) Non-controlling interest (3.2 ) 18.8 0.6 Non-deductible acquisition costs 3.4 — (0.3 ) Federal tax credits (0.8 ) 2.5 0.1 Tax audit settlements and return adjustments 0.5 (3.3 ) — Uncertain tax positions (2.0 ) 1.3 3.9 Valuation allowance — 3.9 — Impacts of '17 Tax Cuts and Jobs Act 120.5 — — Other, net 0.1 (0.6 ) (0.2 ) Effective income tax rate 161.5 % 31.0 % 22.8 %
Significant Components of Deferred Tax Assets and Liabilities	The significant components of our deferred tax assets and liabilities are presented in the table below. December 31, 2017 2016 Deferred tax assets: Compensation and benefits $ 18,048 $ 26,371 Unrecognized tax benefits 30,331 32,808 Fixed assets 5,101 6,627 Deferred revenue 7,732 12,917 Reserves 8,115 14,396 Pension 10,138 17,958 Net operating losses 113,615 171,969 Income recognition on contracts in process 7,335 - Other 12,963 21,089 Gross deferred tax assets 213,378 304,135 Deferred tax liabilities: Goodwill and other intangible assets 54,754 49,976 Income recognition on contracts in process — 7,119 Other 7,015 13,769 Gross deferred tax liabilities 61,769 70,864 Valuation allowance (1,074 ) (988 ) Net deferred tax assets $ 150,535 $ 232,283
Summary of Operating Loss Carryforwards	We and our subsidiaries filed income tax returns in various state and foreign jurisdictions. The Company has available at December 31, 2017, unused Federal and state operating loss carry forwards of $436 million and $421 million, respectively, that may be applied against taxable income and that expire in the years as indicated in the table below. Year of Expiration Federal State 2018-2028 $ — $ 4,997 2029-2031 100,876 84,958 2032-2034 187,519 162,444 2035-2037 147,133 168,658 $ 435,528 $ 421,057
Reconciliation of Change in Unrecognized Income Tax Benefits, Excluding Potential Interest and Penalties	The following table presents a reconciliation of the beginning and ending amounts of unrecognized tax benefits, excluding potential interest and penalties: Year Ended December 31, 2017 2016 2015 Balance at January 1 $ 55,274 $ 58,360 $ 67,927 Additions/reductions for tax positions related to the current year 65 151 4,139 Additions/reductions for tax positions related to prior years — — (11,542 ) Lapse of statute of limitations (2,551 ) (3,237 ) (2,164 ) Balance at December 31 $ 52,788 $ 55,274 $ 58,360

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Based Compensation Expense	Share-based compensation expense is summarized in the table below. Year Ended December 31, 2017 2016 2015 Share-based compensation $ 7,938 $ 8,255 $ 9,297 Income taxes (3,107 ) (3,219 ) (3,622 ) Total after income taxes $ 4,831 $ 5,036 $ 5,675
Summary of Nonvested Restricted Stock Units	The table below presents a summary of our nonvested RSU awards activity for the year ended December 31, 2017. Number of Units Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 571 $ 20.57 Granted 250 30.19 Forfeited (167 ) 22.53 Vested (108 ) 22.76 Nonvested balance at December 31, 2017 546 $ 23.93 Director RSUs vested but not issued at December 31, 2017 63 $ 27.99
Summary of Nonvested Performance Based Units	The table below presents a summary of our nonvested performance share awards as of December 31, 2017. Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 554 $ 22.86 Granted 189 30.54 Forfeited (201 ) 24.90 Vested (33 ) 28.07 Nonvested balance at December 31, 2017 509 24.58
Summary of Nonvested Performance Retention Based Units	The table below presents a summary of our nonvested performance retention awards as of December 31, 2017. Number of Shares Weighted- Average Grant Date Fair Value (in thousands) Nonvested balance at December 31, 2016 99 $ 32.82 Granted — — Forfeited (20 ) 32.82 Vested (20 ) 32.82 Nonvested balance at December 31, 2017 59 $ 32.82

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Payments under Non-cancelable Operating Leases	The following table presents future minimum base rent payments under non-cancellable operating leases with initial terms in excess of one year at December 31, 2017. Real Estate Equipment Total 2018 $ 20,829 $ 127 $ 20,956 2019 17,177 99 17,276 2020 15,139 19 15,158 2021 13,688 — 13,688 2022 10,085 — 10,085 Thereafter 25,310 — 25,310 Total minimum payments required 102,228 245 102,473 Less: Sublease rentals under non-cancellable leases (58 ) — (58 ) Net minimum payments required $ 102,170 $ 245 $ 102,415
Schedule of Rent Expense under Non-cancelable Operating Leases	The following table presents rent expense under non-cancellable operating leases. Year Ended December 31, 2017 2016 2015 Rent expense $ 31,778 $ 38,945 $ 53,912

Employee Benefits (Tables)

Employee Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Postemployment Benefits [Abstract]
Net Periodic Pension Cost	Net Periodic Pension Cost DRC Pension Plan TASC Benefit Plan Year Ended December 31, Year Ended December 31, 2017 2016 2015 2017 2016 2015 (1) Service cost $ 823 $ 805 $ — $ — $ — $ — Interest cost on projected benefit obligations 2,499 2,543 3,997 495 468 470 Expected return on plan assets (3,817 ) (3,813 ) (5,833 ) — — — Net loss (gain) amortization 451 292 231 (72 ) — — Settlement loss — — 3,141 — — — Immediate recognition of benefit cost due to plan termination — — — — — 285 Net periodic benefit income (expense) $ (44 ) $ (173 ) $ 1,536 $ 423 $ 468 $ 755
Obligations and Funded Status	Obligations and Funded Status DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Change in benefit obligation: Benefit obligation at beginning of year $ 77,732 $ 78,665 $ 16,455 $ 18,146 Service cost 823 805 — — Interest cost 2,499 2,543 495 468 Benefits paid (4,508 ) (4,915 ) (333 ) (286 ) Actuarial loss (gain) 1,336 1,506 (272 ) (1,873 ) Administrative expenses paid (867 ) (872 ) — — Benefit obligation at end of year 77,015 77,732 16,345 16,455 Change in plan assets: Fair value of plan assets at beginning of year 48,489 50,130 — — Actual return on plan assets 5,547 3,286 — — Employer contributions 5,748 860 333 286 Benefits paid (4,508 ) (4,915 ) (333 ) (286 ) Administrative expenses paid (867 ) (872 ) — — Fair value of plan assets at end of year 54,409 48,489 — — Unfunded status $ (22,606 ) $ (29,243 ) $ (16,345 ) $ (16,455 )
Schedule of Amounts Recognized in Balance Sheet	Amounts recognized in the consolidated balance sheets consist of: DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Other current liabilities $ — $ — $ 811 $ 714 Other long-term liabilities 22,606 29,243 15,534 15,741 Net amount recognized $ 22,606 $ 29,243 $ 16,345 $ 16,455
Schedule of Defined Benefit Plan Amounts Recognized in Accumulated Other Comprehensive Income (Loss)	DRC Pension Plan Beginning Balance Net Loss Amortization Experience Loss (Gain) Ending Balance 2017 $ 15,976 $ (451 ) $ (394 ) $ 15,131 2016 $ 14,235 $ (292 ) $ 2,033 $ 15,976 2015 $ 14,800 $ (291 ) $ (274 ) $ 14,235 TASC Benefit Plan Beginning Balance Net Gain Amortization Experience Gain Ending Balance 2017 $ (2,077 ) $ 72 $ (271 ) $ (2,276 ) 2016 $ (204 ) $ — $ (1,873 ) $ (2,077 ) 2015 $ — $ — $ (204 ) $ (204 )
Schedule of Assumptions Used to Determine the Benefit Obligations and Net Periodic Benefit Costs	The following assumptions were used to determine the benefit obligations and net periodic benefit costs: Used to determine benefit obligations: DRC Pension Plan TASC Benefit Plan December 31, December 31, 2017 2016 2017 2016 Discount rate 3.53 % 3.95 % 3.33 % 3.54 % Rate of compensation increase N/A N/A N/A N/A Used to determine net periodic benefit costs: DRC Pension Plan TASC Benefit Plan Year Ended December 31, Year Ended December 31, 2017 2016 2015 2017 2016 2015 Discount rate 3.31 % 3.39 % 3.94 % (1) 3.08 % 2.85 % 3.05 % (2) Expected rate of return on assets 7.86 % 8.00 % 8.00 % N/A N/A N/A Rate of compensation increase N/A N/A N/A N/A N/A N/A (1) The discount rate used for the determination of the settlement in 2015 was 4.17%. (2) Represents the discounts rate for the RHRA Plan. The discount rate for the Cash Bonus Plan in 2015 was 0.95%.
Summary of Fair Value Measurement of Plan Assets by Asset Category	The fair value measurement of plan assets by asset category at December 31, 2017 is as follows: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Asset Category Total (Level 1) (Level 2) (Level 3) Equity mutual funds $ 50,733 $ 50,733 $ — $ — Guaranteed deposit account 2,578 — — 2,578 Hedge funds 1,098 — — 1,098 Total $ 54,409 $ 50,733 $ — $ 3,676 The fair value measurement of plan assets by asset category at December 31, 2016 is as follows: Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Asset Category Total (Level 1) (Level 2) (Level 3) Cash $ 301 $ 301 $ — $ — Money market funds 1,653 — 1,653 — Equity securities: Common equity securities 7,340 7,340 — — Equity mutual funds 86 86 — — Real estate investment trusts 43 43 — — Exchanged traded funds equity 17,542 17,542 — — Corporate and foreign bonds 15,101 — 15,101 — Hedge funds 6,423 — — 6,423 Total $ 48,489 $ 25,312 $ 16,754 $ 6,423
Reconciliation of Beginning and Ending Balances of Level 3 Assets	Fair Value Measurement Using Significant Unobservable Inputs (Level 3) A reconciliation of the beginning and ending balances of hedge fund assets is as follows: Guaranteed Deposit Account Hedge Funds Total Balance at December 31, 2015 $ — $ 6,438 $ 6,438 Actual returns on plan assets related to assets still held at the reporting date — 325 325 Purchases — 104 104 Sales — (444 ) (444 ) Balance at December 31, 2016 — 6,423 6,423 Actual returns on plan assets related to assets still held at the reporting date — 123 123 Purchases 2,578 — 2,578 Sales — (5,448 ) (5,448 ) Balance at December 31, 2017 $ 2,578 $ 1,098 $ 3,676
Summary of Expected Timing of Benefit Payments	The following table sets forth the expected timing of benefit payments by fiscal year: DRC Pension Plan TASC Benefit Plan Total 2018 $ 4,966 $ 811 $ 5,777 2019 $ 4,996 $ 874 $ 5,870 2020 $ 5,064 $ 1,052 $ 6,116 2021 $ 5,038 $ 1,263 $ 6,301 2022 $ 5,037 $ 1,420 $ 6,457 Five subsequent fiscal years $ 24,620 $ 7,690 $ 32,310

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Redemption Price as Percentage of Principal Amount	Year Percentage 2019 104.438 2020 102.219 2021 and thereafter 100.000
Schedule of Composition of Debt	The composition of our debt at December 31, 2017 and 2016 was as follows: December 31, 2017 2016 Term Loans $ 713,000 $ 823,300 Notes 300,000 300,000 Other 314 461 Total debt 1,013,314 1,123,761 Less: current portion of long-term debt (26,947 ) (26,947 ) Less: unamortized original issue discount costs and financing fees (47,680 ) (56,821 ) Long-term debt $ 938,687 $ 1,039,993
Summary of Debt Minimum Principal Payments	The following table presents our minimum debt principal payments. Minimum Debt Principal Payments 2018 $ 26,947 2019 26,967 2020 141,800 2021 6,800 2022 6,800 Thereafter 804,000 Total minimum payments required $ 1,013,314

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Summary of Other Terms of Instruments	The other terms of these instruments are as follows: Contract received: Floating interest rate LIBOR (subject to minimum of 1.00%) Contract paid: Fixed interest rates 1.947% - 1.949%
Summary of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents our assets and liabilities that are measured at fair value on a recurring basis: December 31, December 31, Balance Sheet Classification Fair Value Hierarchy 2017 2016 Interest rate swap assets Other assets Level 2 $ 1,129 $ — Interest rate swap liabilities Other current liabilities Level 2 $ (477 ) $ —
Credit Facility 2015 [Member]
Summary of Other Terms of Instruments	The other terms of these instruments were as follows: Contract received: Floating interest rate LIBOR (subject to minimum of 1.25%) Contract paid: Fixed interest rates 3.09% - 3.18%

Restructuring and Integration35

Restructuring and Integration Costs (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Summary of Restructuring and Integration Costs	The activity and balance of the liability accounts are as follows: Severance and Related Costs Other Restructuring Costs Total Balance as of December 31, 2014 $ 368 $ 6,036 $ 6,404 Additions 14,614 6,476 21,090 Cash payments (10,976 ) (3,041 ) (14,017 ) Balance as of December 31, 2015 4,006 9,471 13,477 Additions 9,357 2,186 11,543 Cash payments (12,059 ) (6,704 ) (18,763 ) Other adjustments — (2,429 ) (2,429 ) Balance as of December 31, 2016 1,304 2,524 3,828 Additions — 1,859 1,859 Cash payments (1,304 ) (3,479 ) (4,783 ) Other adjustments — (904 ) (904 ) Balance as of December 31, 2017 $ — $ — $ —

Separate Financial Informatio36

Separate Financial Information of Subsidiary Guarantor of Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Supplemental Condensed Consolidating Balance Sheet	SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 31,966 $ 36 $ 9,888 $ — $ 41,890 Receivables, net — 301,047 9,562 20,485 — 331,094 Intercompany receivables — — 28,069 7,738 (35,807 ) — Other current assets — 17,300 (4 ) 2,385 — 19,681 Total current assets — 350,313 37,663 40,496 (35,807 ) 392,665 Property, plant and equipment, net — 43,933 — 73 — 44,006 Goodwill — 1,071,371 — — — 1,071,371 Identifiable intangible assets, net — 361,410 — — — 361,410 Deferred tax assets — 150,535 — — — 150,535 Investment in subsidiaries 676,105 67,623 31,876 — (775,604 ) — Other assets — 5,976 45 — — 6,021 Total assets $ 676,105 $ 2,051,161 $ 69,584 $ 40,569 $ (811,411 ) $ 2,026,008 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 52,826 — 128 — 52,954 Intercompany payable — 35,807 — — (35,807 ) — Accrued employment costs — 68,622 1,961 6,962 — 77,545 Accrued expenses — 74,657 — 199 — 74,856 Advance payments and billings in excess of costs incurred — 30,380 — — — 30,380 Income tax liabilities — 320 — 228 548 Other current liabilities — 25,512 — 1,176 26,688 Total current liabilities — 315,071 1,961 8,693 (35,807 ) 289,918 Long-term debt — 938,687 — — — 938,687 Income tax liabilities — 62,219 — — — 62,219 Other liabilities — 59,079 — — — 59,079 Total liabilities — 1,375,056 1,961 8,693 (35,807 ) 1,349,903 Shareholders' equity 676,105 676,105 67,623 31,876 (775,604 ) 676,105 Total liabilities and equity $ 676,105 $ 2,051,161 $ 69,584 $ 40,569 $ (811,411 ) $ 2,026,008 SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 31,144 $ 365 $ 16,727 $ — $ 48,236 Receivables, net — 297,334 18,030 18,884 — 334,248 Intercompany receivables — 124,741 — 758 (125,499 ) — Assets held for sale, current — 2,332 17,910 — — 20,242 Other current assets — 27,437 506 2,461 — 30,404 Total current assets — 482,988 36,811 38,830 (125,499 ) 433,130 Property, plant and equipment, net — 46,413 3 131 — 46,547 Goodwill — 1,078,454 — — — 1,078,454 Identifiable intangible assets, net — 393,891 — — — 393,891 Deferred tax assets — 236,457 (4,174 ) — — 232,283 Assets held for sale — 1 11,961 — — 11,962 Investment in subsidiaries 704,805 (60,902 ) 29,248 — (673,151 ) — Other assets — 2,292 — — — 2,292 Total assets $ 704,805 $ 2,179,594 $ 73,849 $ 38,961 $ (798,650 ) $ 2,198,559 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 43,848 37 58 — 43,943 Intercompany payable — 758 124,741 — (125,499 ) — Accrued employment costs — 87,263 4,466 7,131 — 98,860 Accrued expenses — 76,520 — 350 — 76,870 Advance payments and billings in excess of costs incurred — 33,259 — — — 33,259 Income tax liabilities — — — 230 (21 ) 209 Liabilities held for sale, current — — 4,341 — — 4,341 Other current liabilities — 34,398 47 1,944 21 36,410 Total current liabilities — 302,993 133,632 9,713 (125,499 ) 320,839 Long-term debt — 1,039,993 — — — 1,039,993 Income tax liabilities — 64,852 — — — 64,852 Liabilities held for sale — — 1,084 — — 1,084 Other liabilities — 66,951 35 — — 66,986 Total liabilities — 1,474,789 134,751 9,713 (125,499 ) 1,493,754 Shareholders' equity 704,805 704,805 (60,902 ) 29,248 (673,151 ) 704,805 Total liabilities and equity $ 704,805 $ 2,179,594 $ 73,849 $ 38,961 $ (798,650 ) $ 2,198,559
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income (Loss)	SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE YEAR ENDED DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,755,936 $ 32,519 $ 143,432 $ — $ 1,931,887 Costs and expenses Cost of revenue — 1,470,400 56,340 128,989 — 1,655,729 Selling, general and administrative expenses — 134,670 3,287 4,434 — 142,391 Goodwill impairment — 7,083 — — — 7,083 Total costs and expenses — 1,612,153 59,627 133,423 — 1,805,203 Operating income (loss) — 143,783 (27,108 ) 10,009 — 126,684 Interest expense, net — 76,716 — — — 76,716 Other expenses (income), net — (17 ) (4 ) 248 — 227 Income (loss) in equity investments in subsidiaries (35,191 ) (21,920 ) 5,185 — 51,926 — Income (loss) before income taxes (35,191 ) 45,164 (21,919 ) 9,761 51,926 49,741 Provision for income taxes — 80,355 1 — — 80,356 Net income (loss) (35,191 ) (35,191 ) (21,920 ) 9,761 51,926 (30,615 ) Less: Net income attributable to non-controlling interest — — — 4,576 — 4,576 Net income (loss) attributable to Engility $ (35,191 ) $ (35,191 ) $ (21,920 ) $ 5,185 $ 51,926 $ (35,191 ) Net income (loss) $ (35,191 ) $ (35,191 ) $ (21,920 ) $ 9,761 $ 51,926 $ (30,615 ) Other comprehensive income — 1,060 — — — 1,060 Comprehensive income (loss) (35,191 ) (34,131 ) (21,920 ) 9,761 51,926 (29,555 ) Less: Net income attributable to non-controlling interest — — — 4,576 — 4,576 Comprehensive income (loss) attributable to Engility $ (35,191 ) $ (34,131 ) $ (21,920 ) $ 5,185 $ 51,926 $ (34,131 ) SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE LOSS FOR THE YEAR ENDED DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,834,718 $ 87,539 $ 154,166 $ — $ 2,076,423 Costs and expenses Cost of revenue — 1,503,356 133,307 141,181 — 1,777,844 Selling, general and administrative expenses — 145,215 17,964 3,059 — 166,238 Goodwill impairment — 9,875 — — — 9,875 Total costs and expenses — 1,658,446 151,271 144,240 — 1,953,957 Operating income (loss) — 176,272 (63,732 ) 9,926 — 122,466 Interest expense, net — 131,185 — — — 131,185 Other expenses (income), net — (135 ) 1 214 — 80 Income (loss) in equity investments in subsidiaries (10,807 ) (58,753 ) 4,974 — 64,586 — Income (loss) before income taxes (10,807 ) (13,531 ) (58,759 ) 9,712 64,586 (8,799 ) Provision (benefit) for income taxes — (2,724 ) (6 ) — — (2,730 ) Net income (loss) (10,807 ) (10,807 ) (58,753 ) 9,712 64,586 (6,069 ) Less: Net income attributable to non-controlling interest — — — 4,738 — 4,738 Net income (loss) attributable to Engility $ (10,807 ) $ (10,807 ) $ (58,753 ) $ 4,974 $ 64,586 $ (10,807 ) Net income (loss) $ (10,807 ) $ (10,807 ) $ (58,753 ) $ 9,712 $ 64,586 $ (6,069 ) Other comprehensive income — 2,364 — — — 2,364 Comprehensive income (loss) (10,807 ) (8,443 ) (58,753 ) 9,712 64,586 (3,705 ) Less: Net income attributable to non-controlling interest — — — 4,738 — 4,738 Comprehensive income (loss) attributable to Engility $ (10,807 ) $ (8,443 ) $ (58,753 ) $ 4,974 $ 64,586 $ (8,443 ) SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME FOR THE YEAR ENDED DECEMBER 31, 2015 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,796,441 $ 151,514 $ 156,704 $ (19,036 ) $ 2,085,623 Costs and expenses Cost of revenue — 1,519,802 135,985 142,958 (19,036 ) 1,779,709 Selling, general and administrative expenses 184,397 15,162 3,703 — 203,262 Goodwill impairment — 292,100 — — — 292,100 Total costs and expenses — 1,996,299 151,147 146,661 (19,036 ) 2,275,071 Operating income (loss) — (199,858 ) 367 10,043 — (189,448 ) Interest expense (income), net — 110,148 — (5 ) — 110,143 Other expense (income), net — (1,289 ) 4 — — (1,285 ) Income (loss) in equity investments in subsidiaries (235,352 ) 3,018 4,935 — 227,399 — Income (loss) before income taxes (235,352 ) (305,699 ) 5,298 10,048 227,399 (298,306 ) Benefit for income taxes — (70,347 ) 2,280 — — (68,067 ) Net income (loss) (235,352 ) (235,352 ) 3,018 10,048 227,399 (230,239 ) Less: Net income attributable to non-controlling interest — — — 5,113 — 5,113 Net income (loss) attributable to Engility $ (235,352 ) $ (235,352 ) $ 3,018 $ 4,935 $ 227,399 $ (235,352 ) Net income (loss) $ (235,352 ) $ (235,352 ) $ 3,018 $ 10,048 $ 227,399 $ (230,239 ) Other comprehensive income — 1,789 — — — 1,789 Comprehensive income (loss) (235,352 ) (233,563 ) 3,018 10,048 227,399 (228,450 ) Less: Net income attributable to non-controlling interest — — — 5,113 — 5,113 Comprehensive income (loss) attributable to Engility $ (235,352 ) $ (233,563 ) $ 3,018 $ 4,935 $ 227,399 $ (233,563 )
Supplemental Condensed Consolidating Statement of Cash Flows	SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ (62,082 ) $ 152,481 $ 7,274 $ — $ 97,673 Investing activities: Proceeds from sale of business, net of amount placed in escrow — 22,349 — — — 22,349 Proceeds from sale of property, plant and equipment — 2,902 — — — 2,902 Capital expenditures — (9,691 ) — — — (9,691 ) Net cash provided by investing activities — 15,560 — — — 15,560 Financing activities: Repayment of long-term debt — (110,447 ) — — — (110,447 ) Gross borrowings from revolving credit facility — 318,500 — — — 318,500 Repayments of revolving credit facility — (318,500 ) — — — (318,500 ) Payment of employee withholding taxes on share-based compensation (1,501 ) — — — — (1,501 ) Dividends paid (407 ) — — — — (407 ) Distributions to non-controlling interest member — — — (7,133 ) — (7,133 ) Due (to) from subsidiaries 1,908 157,882 (152,810 ) (6,980 ) — — Net cash provided by (used in) financing activities — 47,435 (152,810 ) (14,113 ) — (119,488 ) Change in cash from assets held from sale — (91 ) — — — (91 ) Net change in cash and cash equivalents — 822 (329 ) (6,839 ) — (6,346 ) Cash and cash equivalents, beginning of period — 31,144 365 16,727 — 48,236 Cash and cash equivalents, end of period $ — $ 31,966 $ 36 $ 9,888 $ — $ 41,890 SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ 163,949 $ (82,167 ) $ 12,623 $ — $ 94,405 Investing activities: Capital expenditures — (21,446 ) — — — (21,446 ) Net cash used in investing activities — (21,446 ) — — — (21,446 ) Financing activities: Gross borrowings from issuance of long-term debt — 1,180,000 — — — 1,180,000 Repayment of long-term debt — (1,215,754 ) — — — (1,215,754 ) Gross borrowings from revolving credit facility — 137,000 — — — 137,000 Repayments of revolving credit facility — (137,000 ) — — — (137,000 ) Debt issuance costs — (9,988 ) — — — (9,988 ) Proceeds from share-based payment arrangements 214 — — — — 214 Payment of employee withholding taxes on share-based compensation (1,779 ) — — — — (1,779 ) Dividends paid (1,709 ) — — — — (1,709 ) Distributions to non-controlling interest member — — — (3,865 ) — (3,865 ) Due (to) from subsidiaries 3,274 (82,066 ) 82,503 (3,711 ) — — Net cash provided by (used in) financing activities — (127,808 ) 82,503 (7,576 ) — (52,881 ) Change in cash from assets held from sale — (1,864 ) — — — (1,864 ) Net change in cash and cash equivalents — 12,831 336 5,047 — 18,214 Cash and cash equivalents, beginning of period — 18,313 29 11,680 — 30,022 Cash and cash equivalents, end of period $ — $ 31,144 $ 365 $ 16,727 $ — $ 48,236 SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE YEAR ENDED DECEMBER 31, 2015 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by operating activities $ 5,530 $ 85,842 $ (50,963 ) $ 13,539 $ — $ 53,948 Investing activities: Acquisitions, net of cash acquired — 25,478 — — — 25,478 Capital expenditures — (19,610 ) — — — (19,610 ) Net cash used in investing activities — 5,868 — — — 5,868 Financing activities: Gross borrowings from issuance of long-term debt — 585,000 — — — 585,000 Repayment of long-term debt — (403,674 ) — — — (403,674 ) Gross borrowings from revolving credit facility — 157,000 — — — 157,000 Repayments of revolving credit facility — (115,000 ) — — — (115,000 ) Debt issuance costs — (42,425 ) — — — (42,425 ) Equity issuance costs (2,590 ) — — — — (2,590 ) Proceeds from share-based payment arrangements 279 — — — — 279 Payment of employee withholding taxes on share-based compensation (8,021 ) — — — — (8,021 ) Dividends paid (204,304 ) — — — — (204,304 ) Distributions to non-controlling interest member — — — (3,182 ) — (3,182 ) Due (to) from subsidiaries 209,106 (254,298 ) 47,865 (2,673 ) — — Net cash provided by financing activities (5,530 ) (73,397 ) 47,865 (5,855 ) — (36,917 ) Net change in cash and cash equivalents — 18,313 (3,098 ) 7,684 — 22,899 Cash and cash equivalents, beginning of period — — 3,127 3,996 — 7,123 Cash and cash equivalents, end of period $ — $ 18,313 $ 29 $ 11,680 $ — $ 30,022

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Details)	Jan. 06, 2017USD ($)	Nov. 30, 2016USD ($)	Sep. 29, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)employeeCountryshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Basis of Presentation [Line Items]
Number of individuals employed | employee						8,700
Number of countries in which Company operates | Country						44
Pre-tax income to correct an error related to prior year							$ (2,000,000)
Loss on contract services						$ 1,000,000	1,000,000	$ 2,000,000
Unbilled receivables restructuring costs incurred						$ 9,000,000	11,000,000
Period in which compensation cost estimated to be recognized						3 years
Valuation allowance						$ 1,074,000	988,000
Long-term net deferred tax assets						150,535,000	232,283,000
Impairment charges of identifiable intangible assets						0	0	0
Working capital adjustments finalized			$ 2,000,000
Working capital adjustments loss							1,000,000
Goodwill impairment		$ 0			$ 292,000,000	7,083,000	9,875,000	292,100,000
Long-term assets held for sale				$ 2,000,000			20,242,000
Accumulated depreciation				1,000,000		34,315,000	29,284,000
Gain on sale of long-term assets						$ 302,000	$ (1,078,000)	$ (3,413,000)
Anti-dilutive securities | shares						532,060	766,935	570,181
Selling, General and Administrative Expenses [Member]
Basis of Presentation [Line Items]
Gain on sale of long-term assets				1,000,000
International Resources Group Ltd. [Member]
Basis of Presentation [Line Items]
Initial purchase price	$ 25,000,000
Cash on hand adjustment purchase price			$ 1,000,000
Indemnity escrow				$ 2,000,000
International Resources Group Ltd. [Member] | Discontinued Operations, Held-for-sale [Member]
Basis of Presentation [Line Items]
Goodwill impairment							$ 10,000,000
Minimum [Member]
Basis of Presentation [Line Items]
Useful lives of identifiable intangible assets						1 year
Maximum [Member]
Basis of Presentation [Line Items]
Useful lives of identifiable intangible assets						20 years
Building [Member]
Basis of Presentation [Line Items]
Useful lives of assets						30 years
Machinery, Equipment, Furniture and Fixtures [Member] | Minimum [Member]
Basis of Presentation [Line Items]
Useful lives of assets						3 years
Machinery, Equipment, Furniture and Fixtures [Member] | Maximum [Member]
Basis of Presentation [Line Items]
Useful lives of assets						10 years
Contracts Accounted for under Percentage of Completion [Member]
Basis of Presentation [Line Items]
Financial effect of change in estimate, increase to revenue and operating income (loss)						$ 12,000,000	18,000,000
Award Fees Contracts Accounted For Under Cost-Plus Type Contracts [Member] | Contracts Accounted for under Percentage of Completion [Member]
Basis of Presentation [Line Items]
Financial effect of change in estimate, increase to revenue and operating income (loss)						$ 3,000,000	$ 4,000,000
Engility Corporation [Member]
Basis of Presentation [Line Items]
Capital stock owning percentage by parent						100.00%
Forfeiture Support Associates LLC [Member]
Basis of Presentation [Line Items]
Non-controlling equity interest ownership percentage						50.10%

Basis of Presentation - Carryin

Basis of Presentation - Carrying Amounts of Assets and Liabilities Classified as Held for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets held for sale, current:
Assets held for sale, current	$ 2,000	$ 20,242
Assets held for sale:
Assets held for sale		11,962
Liabilities held for sale, current:
Liabilities held for sale, current		4,341
Liabilities held for sale:
Liabilities held for sale		1,084
Cash and Cash Equivalents [Member]
Assets held for sale, current:
Assets held for sale, current		1,864
Receivables Net [Member]
Assets held for sale, current:
Assets held for sale, current		14,886
Property, Plant and Equipment Net [Member]
Assets held for sale:
Assets held for sale		868
Goodwill [Member]
Assets held for sale:
Assets held for sale		4,849
Identifiable Intangible Assets Net [Member]
Assets held for sale:
Assets held for sale		6,245
Other Current Assets [Member]
Assets held for sale, current:
Assets held for sale, current		3,492
Accounts Payable Trade [Member]
Liabilities held for sale, current:
Liabilities held for sale, current		727
Accrued Expenses [Member]
Liabilities held for sale, current:
Liabilities held for sale, current		3,268
Advance Payments and Billings in Excess of Costs Incurred [Member]
Liabilities held for sale, current:
Liabilities held for sale, current		271
Other Current Liabilities [Member]
Liabilities held for sale, current:
Liabilities held for sale, current		75
Other NonCurrent Liabilities [Member]
Liabilities held for sale:
Liabilities held for sale		$ 1,084

Basis of Presentation - Earning

Basis of Presentation - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss attributable to Engility	$ (35,191)	$ (10,807)	$ (235,352)
Weighted average number of shares outstanding – Basic	36,838	36,730	33,536
Weighted average number of shares outstanding – Diluted	36,838	36,730	33,536
Loss per share attributable to Engility
Basic	$ (0.96)	$ (0.29)	$ (7.02)
Diluted	$ (0.96)	$ (0.29)	$ (7.02)

New Accounting Pronouncements -

New Accounting Pronouncements - Additional Information (Details) - USD ($)	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2015
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Excess tax benefits recognized as a reduction to tax expense		$ 191,000	$ (5,530,000)
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on accumulated deficit, net of tax		1,000,000
Excess tax benefits recognized as a reduction to tax expense		$ 0
Accounting Standards Update 2014-09 [Member] | Maximum [Member] | Subsequent Event [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect on accumulated deficit, net of tax	$ 2,000

Business Acquisitions - Additio

Business Acquisitions - Additional Information (Details) $ / shares in Units, $ in Thousands	Feb. 26, 2018	Feb. 26, 2015USD ($)board_member$ / sharesshares	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Common stock ownership, percent		99.00%
Number of board members eligible to be nominated | board_member		11
Shares issued for acquisition						$ 663,125
Dividends paid		$ 204,000		$ 407	$ 1,709	204,304
Number of board members eligible to be nominated by Engility directors | board_member		7
Number of board members eligible to be nominated, Birch Partners | board_member		4
Acquisition and restructuring related costs				$ 5,000	$ 12,000	$ 45,000
TASC [Member]
Business Acquisition [Line Items]
Common stock ownership, percent		52.00%
Shares issued for acquisition (in shares) | shares		18,937,765
Shares issued for acquisition		$ 663,000
Fair value of debt assumed		623,000
Cash dividends on common stock		$ 207,000
Dividend paid, per share (in USD per share) | $ / shares		$ 11.434
Common stock ownership, maximum percent, before consensus voting		30.00%
Revenue of acquiree since acquisition date			$ 907,000
Pre-tax net income of acquiree since acquisition			$ 55,000
TASC [Member] | Minimum [Member]
Business Acquisition [Line Items]
Common stock ownership, percent required to consensus voting		21.00%
TASC [Member] | Maximum [Member]
Business Acquisition [Line Items]
Common stock ownership, percent required to consensus voting		21.50%
TASC [Member] | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P.
Business Acquisition [Line Items]
Number of board members eligible to be nominated | board_member		4
TASC [Member] | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Minimum [Member]
Business Acquisition [Line Items]
Business combination, period in which ownership can not be transferred		1 year
Business combination, period in which limited ownership can be transferred		4 years
TASC [Member] | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Maximum [Member]
Business Acquisition [Line Items]
Business combination, period in which ownership can not be transferred		3 years
Business combination, period in which limited ownership can be transferred		6 years
TASC [Member] | Scenario 1 | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P.
Business Acquisition [Line Items]
Number of board members eligible to be nominated | board_member		4
TASC [Member] | Scenario 1 | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Minimum [Member]
Business Acquisition [Line Items]
Common stock ownership, percent		50.00%
TASC [Member] | Scenario 2 | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P.
Business Acquisition [Line Items]
Number of board members eligible to be nominated | board_member		2
TASC [Member] | Scenario 2 | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Minimum [Member]
Business Acquisition [Line Items]
Common stock ownership, percent		25.00%
TASC [Member] | Scenario 2 | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Maximum [Member]
Business Acquisition [Line Items]
Common stock ownership, percent		50.00%
TASC [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Common stock ownership, percent	51.00%

Business Acquisitions - TASC Ac

Business Acquisitions - TASC Acquisition (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 26, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchase Price Allocation
Goodwill		$ 1,071,371	$ 1,078,454	$ 1,093,178
TASC [Member]
Purchase Price Allocation
Shares issued for acquisition (in shares)	18,937,765
Share price	$ 46.45
Dividend paid, per share (in USD per share)	11.434
Value of Engility shares issued to TASC stockholders	$ 35.016
Equity consideration	$ 663,125
Cash	25,478
Receivables	149,041
Prepaid and deferred income taxes, current	26,015
Other current assets	26,286
Property, plant and equipment	15,835
Deferred tax assets	175,180
Other assets	5,096
Current portion of long-term debt	(4,097)
Accounts payable, trade	(34,503)
Accrued employment costs	(92,396)
Accrued expenses	(33,387)
Advance payments and billings in excess of costs incurred	(18,004)
Deferred income taxes, current and income taxes payable	(248)
Other current liabilities	(32,522)
Long-term debt	(619,227)
Other long-term liabilities	(24,446)
Identifiable intangible assets	358,300
Goodwill	740,724
Net assets acquired	$ 663,125

Business Acquisitions - Intangi

Business Acquisitions - Intangible Assets (Details) - TASC [Member] $ in Thousands	Feb. 26, 2015USD ($)
Identifiable Intangible Assets
Identifiable intangible assets	$ 358,300
Customer Contractual Relationships [Member]
Identifiable Intangible Assets
Useful Life (years)	15 years
Identifiable intangible assets	$ 333,600
Contractual Backlog [Member]
Identifiable Intangible Assets
Useful Life (years)	1 year
Identifiable intangible assets	$ 17,700
Technology [Member]
Identifiable Intangible Assets
Useful Life (years)	15 years
Identifiable intangible assets	$ 7,000

Business Acquisitions - Pro For

Business Acquisitions - Pro Forma (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Business Acquisition Pro Forma Information [Abstract]
Revenue	$ 2,239,577
Operating (loss) income	$ (143,496)

Receivables - Components of Con

Receivables - Components of Contract Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Billed receivables	$ 119,506	$ 97,661
Unbilled receivables	222,994	248,253
Allowance for doubtful accounts	(11,406)	(11,666)
Total receivables, net	$ 331,094	$ 334,248

Receivables - Additional Inform

Receivables - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Credit risk of total receivables	4.00%

Receivables - Allowance for Dou

Receivables - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 11,666	$ 11,480	$ 1,482
Charged to expense	12	744	10,286
Deductions	(272)	(558)	(288)
Balance at end of year	$ 11,406	$ 11,666	$ 11,480

Goodwill and Identifiable Int48

Goodwill and Identifiable Intangible Assets - Summary of Goodwill (Details) - USD ($)	Nov. 30, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill
Goodwill		$ 2,060,314,000	$ 2,055,465,000	$ 2,055,465,000	$ 2,060,314,000
Accumulated impairment losses		(967,136,000)	(984,094,000)	(977,011,000)	(967,136,000)
Goodwill		1,093,178,000	1,071,371,000	1,078,454,000	1,093,178,000
Impairment charge	$ 0	$ (292,000,000)	$ (7,083,000)	(9,875,000)	$ (292,100,000)
Goodwill allocated to assets held for sale				$ (4,849,000)

Goodwill and Identifiable Int49

Goodwill and Identifiable Intangible Assets - Additional Information (Details)	Nov. 30, 2017USD ($)reporting_unitContract	Nov. 30, 2016USD ($)reporting_unit	Sep. 29, 2017reporting_unitContract	Dec. 31, 2015USD ($)reporting_unit	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Goodwill [Line Items]
Income approach, percent					50.00%
Guideline public company method, percent						50.00%
Number of reporting units | reporting_unit		5	2
Goodwill impairment charge		$ 0		$ 292,000,000	$ 7,083,000	$ 9,875,000	$ 292,100,000
Number of reporting units with declined estimated fair value | reporting_unit				4
Weighted average long-term growth rate, percent	3.00%	9.00%
Weighted average cost of capital, percent	3.00%	9.00%
Number of reporting units with fair value exceeded carrying value | reporting_unit	3	3
Accumulated Amortization					190,819,000	158,338,000
International Resources Group Ltd. [Member]
Goodwill [Line Items]
Goodwill impairment charge					7,083,000	9,875,000	$ 292,100,000
Accumulated Amortization						3,000,000
International Resources Group Ltd. [Member] | Identifiable Intangible Assets [Member]
Goodwill [Line Items]
Assets held for sale						$ 9,000,000
Minimum [Member]
Goodwill [Line Items]
Goodwill impairment analysis, percent fair value exceeds carrying value	20.00%	15.00%
International [Member]
Goodwill [Line Items]
Goodwill impairment charge	$ 7,000,000				$ 7,000,000
Number of primary contracts | Contract	2		1

Goodwill and Identifiable Int50

Goodwill and Identifiable Intangible Assets - Summary of Goodwill by Reporting Units (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 1,071,371	$ 1,078,454	$ 1,093,178
Space Systems [Member]
Goodwill [Line Items]
Goodwill	367,526	288,594
Intelligence Solutions [Member]
Goodwill [Line Items]
Goodwill	318,242	260,129
Defense [Member]
Goodwill [Line Items]
Goodwill	$ 385,603	242,243
Federal Civilian [Member]
Goodwill [Line Items]
Goodwill		187,582
Products [Member]
Goodwill [Line Items]
Goodwill		$ 99,906

Goodwill and Identifiable Int51

Goodwill and Identifiable Intangible Assets - Information on Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 552,229	$ 552,229
Accumulated Amortization	190,819	158,338
Net Carrying Amount	$ 361,410	393,891
Customer Contractual Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	17 years
Gross Carrying Amount	$ 545,229	545,229
Accumulated Amortization	189,497	157,482
Net Carrying Amount	$ 355,732	387,747
Technology [Member]
Finite Lived Intangible Assets [Line Items]
Weighted Average Amortization Period	15 years
Gross Carrying Amount	$ 7,000	7,000
Accumulated Amortization	1,322	856
Net Carrying Amount	$ 5,678	$ 6,144

Goodwill and Identifiable Int52

Goodwill and Identifiable Intangible Assets - Amortization Expense Recorded for Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 32,481	$ 36,491	$ 45,222

Goodwill and Identifiable Int53

Goodwill and Identifiable Intangible Assets - Estimated Amortization Expense for Identifiable Intangible Assets (Details) $ in Thousands	Dec. 31, 2017USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2,018	$ 32,482
2,019	32,482
2,020	32,482
2,021	32,482
2,022	$ 32,482

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 78,321		$ 75,831
Accumulated depreciation and amortization	(34,315)	$ (1,000)	(29,284)
Property, plant and equipment, net	44,006		46,547
Land [Member]
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	900		900
Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	850		850
Machinery, Equipment, Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	31,208		28,622
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	41,757		43,598
Assets Under Construction [Member]
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 3,606		$ 1,861

Property, Plant and Equipment55

Property, Plant and Equipment - Schedule of Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation expense	$ 12,091	$ 10,306	$ 13,213

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Effective income tax rate		35.00%	35.00%	35.00%
Provisional tax effects of 2017 change in tax rate income tax expense (benefit)		$ 60,000
Foreign tax credits		1,000	$ 1,000
Deferred tax asset, valuation allowance		1,074	988
Unrecognized tax benefits		52,788	55,274	$ 58,360	$ 67,927
Accrued interest and penalty		9,000	10,000	10,000
Unrecognized tax benefits that would impact effective tax rate		9,000
Anticipated decrease in unrecognized tax benefits over the next 12 months		27,000
Accrued potential interest		9,000	10,000
Interest benefit included in income tax expense		1,000	$ 1,000	$ 2,000
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Reversal of foreign reserve		2,000
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Reversal of foreign reserve		3,000
Resolution of Foreign Uncertain Tax Position [Member]
Operating Loss Carryforwards [Line Items]
Anticipated decrease in unrecognized tax benefits over the next 12 months		26,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		435,528
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward		$ 421,057
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Effective income tax rate	21.00%

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income from Continuing Operations before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 49,114	$ (9,285)	$ (298,644)
Foreign	627	486	338
Income (loss) before provision for income taxes	$ 49,741	$ (8,799)	$ (298,306)

Income Taxes - Components of Cu

Income Taxes - Components of Current and Deferred Portions of Provision for Income Taxes from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current income tax provision (benefit):
Federal	$ (2,678)	$ (4,030)	$ (29,632)
State and local	301	107	(1,569)
Foreign	105	(14)	727
Subtotal	(2,272)	(3,937)	(30,474)
Deferred income tax provision (benefit):
Federal	84,464	2,252	(31,830)
State and local	(1,836)	(1,089)	(5,718)
Foreign		44	(45)
Subtotal	82,628	1,207	(37,593)
Total provision (benefit) for income taxes	$ 80,356	$ (2,730)	$ (68,067)

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation from Continuing Operations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory Federal income tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of Federal income tax benefit	3.00%	6.60%	1.70%
Goodwill impairment	5.00%	(33.20%)	(18.00%)
Non-controlling interest	(3.20%)	18.80%	0.60%
Non-deductible acquisition costs	3.40%	0.00%	(0.30%)
Federal tax credits	(0.80%)	2.50%	0.10%
Tax audit settlements and return adjustments	0.50%	(3.30%)	(0.00%)
Uncertain tax positions	(2.00%)	1.30%	3.90%
Valuation allowance	0.00%	3.90%	0.00%
Impacts of '17 Tax Cuts and Jobs Act	120.50%	0.00%	0.00%
Other, net	0.10%	(0.60%)	(0.20%)
Effective income tax rate	161.50%	31.00%	22.80%

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Compensation and benefits	$ 18,048	$ 26,371
Unrecognized tax benefits	30,331	32,808
Fixed assets	5,101	6,627
Deferred revenue	7,732	12,917
Reserves	8,115	14,396
Pension	10,138	17,958
Net operating losses	113,615	171,969
Income recognition on contracts in process	7,335	0
Other	12,963	21,089
Gross deferred tax assets	213,378	304,135
Deferred tax liabilities:
Goodwill and other intangible assets	54,754	49,976
Income recognition on contracts in process	0	7,119
Other	7,015	13,769
Gross deferred tax liabilities	61,769	70,864
Valuation allowance	(1,074)	(988)
Net deferred tax assets	$ 150,535	$ 232,283

Income Taxes Income Taxes - Sum

Income Taxes Income Taxes - Summary of Operating Loss Carryforwards (Details) $ in Thousands	Dec. 31, 2017USD ($)
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 435,528
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	421,057
2018-2028 [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	4,997
2029-2031 [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	100,876
2029-2031 [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	84,958
2032-2034 [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	187,519
2032-2034 [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	162,444
2035-2037 [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	147,133
2035-2037 [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforward	$ 168,658

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Change in Unrecognized Income Tax Benefits, Excluding Potential Interest and Penalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 55,274	$ 58,360	$ 67,927
Additions/reductions for tax positions related to the current year	65	151	4,139
Additions/reductions for tax positions related to prior years	0	0	(11,542)
Lapse of statute of limitations	(2,551)	(3,237)	(2,164)
Ending Balance	$ 52,788	$ 55,274	$ 58,360

Share-Based Compensation - Shar

Share-Based Compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based compensation	$ 7,938	$ 8,255	$ 9,297
Income taxes	(3,107)	(3,219)	(3,622)
Total after income taxes	$ 4,831	$ 5,036	$ 5,675

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost | $	$ 9
Period for recognition	3 years
Unrecognized compensation cost amortized, 2018 | $	$ 6
Unrecognized compensation cost amortized, 2019 | $	$ 3
Immaterial amount amortized year	2,020
Threshold percentage of fair market value of shares under stock options	25.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated vesting (in shares)	364,983
Restricted Stock Units (RSUs) [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Waived vesting (in shares)	229,166
Restricted Stock Units (RSUs) [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated vesting (in shares)	43,950
Waived vesting (in shares)	11,790
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Shares [Member] | 2014 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	100.00%
Performance Shares [Member] | 2013 Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	127.00%

Share-Based Compensation - Long

Share-Based Compensation - Long Term Performance Plan - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	189,000
Weighted average share price (USD per share)	$ 30.54
Shares vested in period (in shares)	33,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average share price (USD per share)	$ 30.19	$ 18.92	$ 32.12
Restricted Stock Units (RSUs) [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	220,194
Weighted average share price (USD per share)	$ 30.44
Vesting period	3 years
Restricted Stock Units (RSUs) [Member] | Employees [Member] | Period One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	775
Restricted Stock Units (RSUs) [Member] | Employees [Member] | Period Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	12,137
Restricted Stock Units (RSUs) [Member] | Employees [Member] | Over Period One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	207,282
Restricted Stock Units (RSUs) [Member] | Non-management Members Of The Board Of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	29,431
Weighted average share price (USD per share)	$ 28.25
Vesting period	1 year
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average share price (USD per share)	$ 30.54	$ 19.33	32.29
Vesting period	3 years
Performance Shares [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	189,351
Weighted average share price (USD per share)	$ 30.54
Shares granted at maximum performance level	568,053
Performance period	3 years
Percent of the target grant amount	100.00%
Performance Shares [Member] | Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	0.00%
Performance Shares [Member] | Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	300.00%
Performance Retention Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	20,000
Performance Retention Award [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average share price (USD per share)			$ 32.82
Performance period	3 years
Percent of the target grant amount	50.00%

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Nonvested Restricted Based Units (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Employee RSUs vested (in shares) | shares	(33)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share)	$ 22.86
Weighted-average grant date fair value, granted (USD per share)	30.54
Weighted-average grant date fair value, forfeited (USD per share)	24.90
Weighted average grant date fair value, employee RSUs vested (USD per share)	28.07
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share)	$ 24.58
Nonvested Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Non-vested units, beginning balance, outstanding (in shares) | shares	571
Granted (in shares) | shares	250
Forfeited (in shares) | shares	(167)
Employee RSUs vested (in shares) | shares	(108)
Non-vested units, ending balance, outstanding (in shares) | shares	546
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share)	$ 20.57
Weighted-average grant date fair value, granted (USD per share)	30.19
Weighted-average grant date fair value, forfeited (USD per share)	22.53
Weighted average grant date fair value, employee RSUs vested (USD per share)	22.76
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share)	23.93
Weighted-average grant date fair value, director RSUs vested but not issued (USD per share)	$ 27.99
Nonvested Restricted Stock Units [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]
Number of units, Director RSUs vested but not issued at December 31, 2016 | shares	63

Share-Based Compensation - Su67

Share-Based Compensation - Summary of Nonvested Performance Based Units (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of shares, nonvested, beginning balance (in shares) | shares	554
Number of shares, granted (in shares) | shares	189
Number of shares, forfeited (in shares) | shares	(201)
Number of shares, vested (in shares) | shares	(33)
Number of shares, nonvested, ending balance (in shares) | shares	509
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 22.86
Weighted-average grant date fair value, granted (USD per share) | $ / shares	30.54
Weighted-average grant date fair value, forfeited (USD per share) | $ / shares	24.90
Weighted average grant date fair value, employee RSUs vested (USD per share) | $ / shares	28.07
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 24.58

Share-Based Compensation - Su68

Share-Based Compensation - Summary of Nonvested Performance Retention Based Units (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of shares, nonvested, beginning balance (in shares) | shares	554
Number of shares, granted (in shares) | shares	189
Number of shares, forfeited (in shares) | shares	(201)
Number of shares, vested (in shares) | shares	(33)
Number of shares, nonvested, ending balance (in shares) | shares	509
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 22.86
Weighted-average grant date fair value, granted (USD per share) | $ / shares	30.54
Weighted-average grant date fair value, forfeited (USD per share) | $ / shares	24.90
Weighted average grant date fair value, vested (USD per share) | $ / shares	28.07
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 24.58
Performance Retention Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of shares, nonvested, beginning balance (in shares) | shares	99
Number of shares, forfeited (in shares) | shares	(20)
Number of shares, vested (in shares) | shares	(20)
Number of shares, nonvested, ending balance (in shares) | shares	59
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 32.82
Weighted-average grant date fair value, forfeited (USD per share) | $ / shares	32.82
Weighted average grant date fair value, vested (USD per share) | $ / shares	32.82
Weighted-average grant date fair value, nonvested weighted-average grant date fair value (USD per share) | $ / shares	$ 32.82

Share-Based Compensation - Empl

Share-Based Compensation - Employee Stock Purchase Plan - Additional Information (Details) - 2016 ESPP [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share purchases offering period	6 months
Percentage of fair market value of options to be purchased	90.00%
Share purchases funded through payroll deduction	10.00%
Share purchases funded through payroll deduction, value	$ 25
Stock issued during period to employees, shares,	78,140	32,848
Stock issued during period to employees, average price per share	$ 25.34	$ 30.50

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Payments under Non-cancelable Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)
Contingencies And Commitments [Line Items]
2,018	$ 20,956
2,019	17,276
2,020	15,158
2,021	13,688
2,022	10,085
Thereafter	25,310
Total minimum payments required	102,473
Less: Sublease rentals under non-cancellable leases	(58)
Net minimum payments required	102,415
Real Estate [Member]
Contingencies And Commitments [Line Items]
2,018	20,829
2,019	17,177
2,020	15,139
2,021	13,688
2,022	10,085
Thereafter	25,310
Total minimum payments required	102,228
Less: Sublease rentals under non-cancellable leases	(58)
Net minimum payments required	102,170
Equipment [Member]
Contingencies And Commitments [Line Items]
2,018	127
2,019	99
2,020	19
2,021	0
2,022	0
Thereafter	0
Total minimum payments required	245
Less: Sublease rentals under non-cancellable leases	0
Net minimum payments required	$ 245

Commitments and Contingencies71

Commitments and Contingencies - Schedule of Rent Expense under Non-cancelable Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Rent expense	$ 31,778	$ 38,945	$ 53,912

Commitments and Contingencies72

Commitments and Contingencies - Additional Information (Details) $ in Millions	Dec. 31, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
Outstanding letters of credit	$ 2

Employee Benefits - Additional

Employee Benefits - Additional Information (Details) $ in Thousands	1 Months Ended	10 Months Ended	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)planFundshares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of plans offered | plan			2
Number of hedge funds in hedge fund assets | Fund			1
Guaranteed Deposit Account [Member]
Defined Benefit Plan Disclosure [Line Items]
Investments credit rating			the average credit quality of the portfolio was AA-
Average maturity for portfolio investments			3 years 8 months 12 days
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Second hedge funds sold as funds of funds to achieve objectives term			3 years
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Second hedge funds sold as funds of funds to achieve objectives term			5 years
Engility Savings Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Matching contribution of employer of initial contribution by employee			50.00%	100.00%
Initial matching percentage of employees contribution, employer will match			8.00%	3.00%
Maximum employer matching contribution percent of employees gross pay			4.00%
Employer contribution matching percentage of additional contribution by employee				50.00%
Employer matching percentage of additional contribution by employee, employer will match				3.00%
Company's contribution under employee savings plan			$ 22,000	$ 26,000	$ 4,000
TASC Defined Contribution Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Matching contribution of employer of initial contribution by employee				100.00%
Initial matching percentage of employees contribution, employer will match				3.00%
Employer contribution matching percentage of additional contribution by employee				50.00%
Employer matching percentage of additional contribution by employee, employer will match				2.00%
Company's contribution under employee savings plan		$ 14,000
Cash Bonus Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Termination of benefits	$ 3,000
DRC Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Termination of benefits	17,000
Settlement charge	3,000
Expected employer contributions to fund plan			0
Combined projected benefit obligation	$ 78,665	$ 78,665	$ 77,015	$ 77,732	$ 78,665
Long-term rate of return			7.50%
Securities included in plan assets | shares			0	0
DRC Defined Benefit Pension Plan [Member] | Minimum [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			45.00%
DRC Defined Benefit Pension Plan [Member] | Minimum [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			30.00%
DRC Defined Benefit Pension Plan [Member] | Minimum [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			0.00%
DRC Defined Benefit Pension Plan [Member] | Minimum [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			2.00%
DRC Defined Benefit Pension Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Cap on Company's stock in fund			3.00%
DRC Defined Benefit Pension Plan [Member] | Maximum [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			65.00%
DRC Defined Benefit Pension Plan [Member] | Maximum [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			50.00%
DRC Defined Benefit Pension Plan [Member] | Maximum [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			20.00%
DRC Defined Benefit Pension Plan [Member] | Maximum [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Target plan asset allocations			10.00%
DRC Pension Plan and TASC Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Combined projected benefit obligation			$ 93,000	$ 94,000

Employee Benefits - Net Periodi

Employee Benefits - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
DRC Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 823	$ 805
Interest cost on projected benefit obligations	2,499	2,543	$ 3,997
Expected return on plan assets	(3,817)	(3,813)	(5,833)
Net loss (gain) amortization	451	292	231
Settlement loss			3,141
Net periodic benefit income (expense)	(44)	(173)	1,536
TASC Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Interest cost on projected benefit obligations	495	468	470
Net loss (gain) amortization	(72)
Immediate recognition of benefit cost due to plan termination			285
Net periodic benefit income (expense)	$ 423	$ 468	$ 755

Employee Benefits - Obligations

Employee Benefits - Obligations and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets:
Fair value of plan assets at beginning of year	$ 48,489
Fair value of plan assets at end of year	54,409	$ 48,489
DRC Pension Plan [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	77,732	78,665
Service cost	823	805
Interest cost	2,499	2,543	$ 3,997
Benefits paid	(4,508)	(4,915)
Actuarial loss (gain)	1,336	1,506
Administrative expenses paid	(867)	(872)
Benefit obligation at end of year	77,015	77,732	78,665
Change in plan assets:
Fair value of plan assets at beginning of year	48,489	50,130
Actual return on plan assets	5,547	3,286
Employer contributions	5,748	860
Benefits paid	(4,508)	(4,915)
Administrative expenses paid	(867)	(872)
Fair value of plan assets at end of year	54,409	48,489	50,130
Unfunded status	(22,606)	(29,243)
TASC Benefit Plan [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	16,455	18,146
Interest cost	495	468	470
Benefits paid	(333)	(286)
Actuarial loss (gain)	(272)	(1,873)
Benefit obligation at end of year	16,345	16,455	$ 18,146
Change in plan assets:
Employer contributions	333	286
Benefits paid	(333)	(286)
Unfunded status	$ (16,345)	$ (16,455)

Employee Benefits - Amounts Rec

Employee Benefits - Amounts Recognized in the Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
DRC Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities		$ 0
Other long-term liabilities	$ 22,606	29,243
Net amount recognized	22,606	29,243
TASC Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Other current liabilities	811	714
Other long-term liabilities	15,534	15,741
Net amount recognized	$ 16,345	$ 16,455

Employee Benefits - Components

Employee Benefits - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 704,805	$ 706,133	$ 476,753
Ending Balance	676,105	704,805	706,133
DRC Pension Plan [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net (Loss) Gain Amortization	(451)	(292)	(291)
DRC Pension Plan [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	15,976	14,235	14,800
Experience Loss (Gain)	(394)	2,033	(274)
Ending Balance	15,131	15,976	14,235
TASC Benefit Plan [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net (Loss) Gain Amortization	72	0	0
TASC Benefit Plan [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(2,077)	(204)	0
Experience Loss (Gain)	(271)	(1,873)	(204)
Ending Balance	$ (2,276)	$ (2,077)	$ (204)

Employee Benefits - Assumptions

Employee Benefits - Assumptions Used In Calculations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
DRC Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.53%	3.95%
Discount rate	3.31%	3.39%	3.94%
Expected rate of return on assets	7.86%	8.00%	8.00%
Settlement discount rate			4.17%
TASC Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.33%	3.54%
Discount rate	3.08%	2.85%	3.05%
Cash Bonus Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate			0.95%

Employee Benefits - Summary of

Employee Benefits - Summary of Fair Value Measurement of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 54,409	$ 48,489
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		301
Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,653
Common Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		7,340
Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50,733	86
Real Estate Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		43
Guaranteed Deposit Account [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,578
ExchangeTradedFundsMember
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		17,542
Corporate and Foreign Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15,101
Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,098	6,423
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50,733	25,312
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		301
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		7,340
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50,733	86
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Real Estate Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		43
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | ExchangeTradedFundsMember
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		17,542
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate and Foreign Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		16,754
Significant Other Observable Inputs (Level 2) [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,653
Significant Other Observable Inputs (Level 2) [Member] | Common Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member] | Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member] | Real Estate Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member] | ExchangeTradedFundsMember
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Other Observable Inputs (Level 2) [Member] | Corporate and Foreign Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15,101
Significant Other Observable Inputs (Level 2) [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,676	6,423	$ 6,438
Significant Unobservable Inputs (Level 3) [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Common Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Real Estate Investment Trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Guaranteed Deposit Account [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,578	0
Significant Unobservable Inputs (Level 3) [Member] | ExchangeTradedFundsMember
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Corporate and Foreign Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Significant Unobservable Inputs (Level 3) [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,098	$ 6,423	$ 6,438

Employee Benefits - Reconciliat

Employee Benefits - Reconciliation of Fair Value Level 3 Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	$ 48,489
Fair value of plan assets at end of year	54,409	$ 48,489
Guaranteed Deposit Account [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at end of year	2,578
Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	6,423
Fair value of plan assets at end of year	1,098	6,423
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	6,423	6,438
Actual returns on plan assets related to assets still held at the reporting date	123	325
Purchases	2,578	104
Sales	(5,448)	(444)
Fair value of plan assets at end of year	3,676	6,423
Significant Unobservable Inputs (Level 3) [Member] | Guaranteed Deposit Account [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	0
Purchases	2,578	0
Fair value of plan assets at end of year	2,578	0
Significant Unobservable Inputs (Level 3) [Member] | Hedge Funds [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	6,423	6,438
Actual returns on plan assets related to assets still held at the reporting date	123	325
Purchases		104
Sales	(5,448)	(444)
Fair value of plan assets at end of year	$ 1,098	$ 6,423

Employee Benefits - Summary o81

Employee Benefits - Summary of Expected Benefit Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,018	$ 5,777
2,019	5,870
2,020	6,116
2,021	6,301
2,022	6,457
Five subsequent fiscal years	32,310
DRC Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,018	4,966
2,019	4,996
2,020	5,064
2,021	5,038
2,022	5,037
Five subsequent fiscal years	24,620
TASC Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2,018	811
2,019	874
2,020	1,052
2,021	1,263
2,022	1,420
Five subsequent fiscal years	$ 7,690

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Aug. 14, 2017	Feb. 13, 2017	Aug. 12, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Gross borrowings from issuance of long-term debt			$ 585,000		$ 1,180,000,000	$ 585,000,000
Repayment of term loan debt				$ 318,500,000	137,000,000	115,000,000
Average outstanding loan amount				$ 1,073,000,000	$ 1,147,000,000	$ 1,077,000,000
Interest rate during period				5.91%	8.07%	8.22%
2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			1,045,000,000
Additional borrowing capacity			$ 150,000,000
First lien secured leverage ratio			4.00%
Commitment fee percentage			0.50%
Debt instrument prepayment premium percentage			1.00%
Percentage of annual excess cash flow for prepayment of loan			50.00%
Prepayment of outstanding term loan as percentage of net cash proceeds of non-ordinary course asset sales or other non-ordinary course dispositions of property or certain casualty events			100.00%
Required investment period of net cash proceeds of non-ordinary course asset sales or other non-ordinary course dispositions of property or certain casualty events			450 days
Prepayment of outstanding term loan percentage of net cash proceeds from issuance of debt except twenty sixteen credit facility			100.00%
Secured debt To EBITDA ratio			6.125%
Consolidated net leverage ratio				3.25%
Repayment of term loan debt				$ 110,000,000
Current borrowing capacity				163,000,000
Debt issuances costs					$ 11,000,000
2016 Credit Facility [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit, amount outstanding				2,000,000
2016 Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Commitment to reinvest net cash proceeds of non-ordinary course asset sales or other non-ordinary course dispositions of property or certain casualty events period			450 days
2016 Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Commitment to reinvest net cash proceeds of non-ordinary course asset sales or other non-ordinary course dispositions of property or certain casualty events period			630 days
2016 Credit Facility [Member] | Company’s Net First Lien Secured Leverage Ratio is not Greater than 3.50:1.00 [Member]
Debt Instrument [Line Items]
Percentage of annual excess cash flow for prepayment of loan			25.00%
Net first lien secured leverage ratio, option one			3.50%
2016 Credit Facility [Member] | Company’s Net First Lien Secured Leverage Ratio is not Greater than 3.00:1.00 [Member]
Debt Instrument [Line Items]
Percentage of annual excess cash flow for prepayment of loan			0.00%
Net first lien secured leverage ratio, option two			3.00%
Credit Facilities 2015 [Member]
Debt Instrument [Line Items]
Early termination penalty					10,000,000
Credit Facilities 2015 [Member] | Interest Expense [Member]
Debt Instrument [Line Items]
Debt issuance costs expensed					$ 5,000,000
Original First Lien Term Facility [Member] | Senior Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 395,000,000
First Lien Credit Agreement and Second Lien Credit Agreement [Member] | Incremental Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			50,000,000
Original Second Lien Term Facility [Member] | Incremental Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			250,000,000
Incremental First Lien Term Facility [Member] | Senior Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Total credit facility			435,000,000
Additional Senior Secured First Lien Revolving Credit Capacity [Member] | Incremental Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			65,000,000
Incremental Second Lien Term Facility [Member] | Senior Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 150,000,000
Second Lien Credit Agreement [Member]
Debt Instrument [Line Items]
Interest percentage			12.00%
Term Loan [Member]
Debt Instrument [Line Items]
Early termination penalty				3,000,000
Two Thousand And Thirteen Credit Facility
Debt Instrument [Line Items]
Debt issuances costs						$ 5,000,000
Two Thousand And Thirteen Credit Facility | Interest Expense [Member]
Debt Instrument [Line Items]
Debt issuance costs expensed						$ 1,000,000
Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility		$ 195,000,000	$ 200,000,000
Debt instrument maturity date					Aug. 12, 2020
Quarterly payment of term loan, percentage					2.50%
Term B2 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility		608,000,000	680,000,000
Debt instrument maturity date					Aug. 12, 2023
Quarterly payment of term loan, percentage					0.25%
Prepayment of term loan debt				$ 83,000,000
Senior Secured Revolving Credit Facility [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			165,000,000
Debt instrument maturity date					Aug. 12, 2021
Senior Secured Revolving Credit Facility [Member] | Credit Facilities 2015 [Member]
Debt Instrument [Line Items]
Total credit facility			115,000,000
Subfacilities for Issuance Letters of Credit [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			35,000,000
Swingline Commitment for Swingline Borrowings [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 35,000,000
8.875% Senior Notes Due 2024 [Member] | Guarantees [Member]
Debt Instrument [Line Items]
Debt instrument maturity date			Sep. 1, 2024
Senior notes issued			$ 300,000,000
Interest percentage			8.875%
Maturity year			2,024
Guarantor obligation term				The Guarantee of the Notes by each Guarantor is: (i) a general senior obligation of such Guarantor; (ii) equal in right of payment to all existing and future indebtedness of such Guarantor that is not subordinated in right of payment to its Guarantee of the Notes (including its guarantee of the 2016 Credit Facility); (iii) effectively subordinated to any existing and future indebtedness of such Guarantor that is secured with property or assets of such Guarantor to the extent of the value of such property and assets securing such indebtedness (including the 2016 Credit Facility); and (iv) senior in right of payment to any future indebtedness of such Guarantor that is expressly subordinated in right of payment of the Notes
Interest payments term				Interest on the Notes is payable on March 1 and September 1 of each year, beginning on March 1, 2017, with the Notes maturing on September 1, 2024
Redemption date			Sep. 1, 2019
Redemption price percentages of the principal amount			100.00%
8.875% Senior Notes Due 2024 [Member] | Indenture [Member]
Debt Instrument [Line Items]
Redemption price percentages of the principal amount			108.875%
Debt instrument percentage redeemable with cash proceeds of equity offerings			35.00%
Percentage of aggregate principal amount of notes that should be outstanding after redemption			60.00%
Debt instrument, redemption period			120 days
Debt instrument redemption price to be offered as percentage of face amount of notes			101.00%
Percentage of aggregate principal amount of Notes holders should own to declare Notes immediately payable if default occurs			30.00%
Senior Secured Term Loan [Member] | Credit Facilities 2015 [Member] | First Lien Term Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 830,000,000
Senior Secured Term Loan [Member] | Credit Facilities 2015 [Member] | Second Lien Term Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 400,000,000
Morgan Stanley [Member] | Amendment Two [Member]
Debt Instrument [Line Items]
Borrowing capacity, description				The Second Amendment was accomplished by (i) the Borrower obtaining new term B1 loan commitments (Term B1 Loans) to refinance the Existing Term B1 Loans and Morgan Stanley making additional Term B1 Loans to the Borrower in a principal amount equal to $185 million minus the principal amount of any Existing Term B1 Loans outstanding on the Second Amendment Effective Date that were converted into Term B1 Loans on the Second Amendment Effective Date, and (ii) the Borrower obtaining new term B2 loan commitments (Term B2 Loans) to refinance the Existing Term B2 Loans and Morgan Stanley making additional Term B2 Loans to the Borrower in a principal amount equal to $579 million minus the principal amount of any Existing Term B2 Loans outstanding on the Second Amendment Effective Date that were converted into Term B2 Loans on the Second Amendment Effective Date. The proceeds of the Term B1 Loans and Term B2 Loans, respectively, will be applied to repay in full the Existing Term B1 Loans and Existing Term B2 Loans, respectively, outstanding as of the Second Amendment Effective Date.
Morgan Stanley [Member] | First Amendment [Member]
Debt Instrument [Line Items]
Borrowing capacity, description				The First Amendment was accomplished by (i) the Borrower obtaining new term B1 loan commitments (New Term B1 Loans) to reprice the Existing Term B1 Loans and Morgan Stanley making additional New Term B1 Loans to the Borrower in a principal amount equal to $195 million minus the principal amount of any Existing Term B1 Loans outstanding on the First Amendment Effective Date that were converted into New Term B1 Loans on the First Amendment Effective Date, and (ii) the Borrower obtaining new term B2 loan commitments (New Term B2 Loans) to reprice the Existing Term B2 Loans and Morgan Stanley making additional New Term B2 Loans to the Borrower in a principal amount equal to $608 million minus the principal amount of any Existing Term B2 Loans outstanding on the First Amendment Effective Date that were converted into New Term B2 Loans on the First Amendment Effective Date. The proceeds of the New Term B1 Loans and New Term B2 Loans, respectively, were applied to repay in full the Existing Term B1 Loans and Existing Term B2 Loans, respectively, outstanding as of the First Amendment Effective Date.
Morgan Stanley [Member] | Term B1 Loan [Member] | Amendment Two [Member]
Debt Instrument [Line Items]
Additional borrowing capacity	$ 185,000,000
Morgan Stanley [Member] | Term B2 Loan [Member] | Amendment Two [Member]
Debt Instrument [Line Items]
Additional borrowing capacity	$ 579,000,000
Morgan Stanley [Member] | New Term B1 Loans [Member] | First Amendment [Member]
Debt Instrument [Line Items]
Additional borrowing capacity		195,000,000
Morgan Stanley [Member] | New Term B2 Loans [Member] | First Amendment [Member]
Debt Instrument [Line Items]
Additional borrowing capacity		$ 608,000,000
Base Rate Loans [Member] | First Lien Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			5.00%
Base Rate Loans [Member] | Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%	2.25%	3.25%
Variable rate floor			0.00%
Base Rate Loans [Member] | Term B2 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%	2.75%	3.75%
Variable rate floor			1.00%
Base Rate Loans [Member] | Senior Secured Revolving Credit Facility [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Variable rate floor			0.00%
Eurocurrency Loans [Member] | Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%	3.25%	4.25%
Eurocurrency Loans [Member] | Term B2 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	3.25%	3.75%	4.75%
Federal Funds Effective Swap Rate [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Federal Funds Effective Swap Rate [Member] | Credit Facilities 2015 [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
London Interbank Offered Rate (LIBOR) [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
London Interbank Offered Rate (LIBOR) [Member] | Credit Facilities 2015 [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Variable rate floor			1.00%
London Interbank Offered Rate (LIBOR) [Member] | First Lien Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate			6.00%
London Interbank Offered Rate (LIBOR) [Member] | Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Variable rate floor			0.00%
London Interbank Offered Rate (LIBOR) [Member] | Term B2 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Variable rate floor			1.00%
London Interbank Offered Rate (LIBOR) [Member] | Senior Secured Revolving Credit Facility [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Variable rate floor			0.00%

Debt - Schedule of Redemption P

Debt - Schedule of Redemption Price as Percentage of Principal Amount (Details)	Aug. 12, 2016
2019 [Member]
Debt Instrument Redemption [Line Items]
Percentage	104.438%
2020 [Member]
Debt Instrument Redemption [Line Items]
Percentage	102.219%
2021 and Thereafter [Member]
Debt Instrument Redemption [Line Items]
Percentage	100.00%

Debt - Schedule of Composition

Debt - Schedule of Composition of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total debt	$ 1,013,314	$ 1,123,761
Less: current portion of long-term debt	(26,947)	(26,947)
Less: unamortized original issue discount costs and financing fees	(47,680)	(56,821)
Long-term debt	938,687	1,039,993
Notes [Member]
Debt Instrument [Line Items]
Total debt	300,000	300,000
Term Loan [Member]
Debt Instrument [Line Items]
Total debt	713,000	823,300
Other [Member]
Debt Instrument [Line Items]
Total debt	$ 314	$ 461

Debt - Summary of Debt Minimum

Debt - Summary of Debt Minimum Principal Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Minimum Debt Principal Payments
2,018	$ 26,947
2,019	26,967
2,020	141,800
2,021	6,800
2,022	6,800
Thereafter	804,000
Total minimum payments required	$ 1,013,314

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, expiration date	Dec. 31, 2020	Dec. 31, 2016
Interest Rate Swap Agreements [Member] | Credit Facility 2015 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Early termination penalty		$ 2
Credit facility termination loss		1
Interest Rate Swap Effective December 29, 2017 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount	$ 281
Interest Rate Swap Effective December 31, 2015 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount		$ 200

Fair Value Measurements - Other

Fair Value Measurements - Other Terms of Instruments (Details) - Interest Rate Swap [Member]	Dec. 31, 2017	Dec. 31, 2016
London Interbank Offered Rate (LIBOR) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, swaption interest rate	1.00%	1.25%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fixed interest rate	1.947%	3.09%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fixed interest rate	1.949%	3.18%

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring [Member] - Level 2 [Member] $ in Thousands	Dec. 31, 2017USD ($)
Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap assets	$ 1,129
Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liabilities	$ (477)

Restructuring and Integration89

Restructuring and Integration Costs - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring And Related Activities [Abstract]
Lease termination fees	$ 2
Restructuring costs		$ 12	$ 21

Restructuring and Integration90

Restructuring and Integration Costs - Summary of Restructuring and Integration Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 3,828	$ 13,477	$ 6,404
Additions	1,859	11,543	21,090
Cash payments	(4,783)	(18,763)	(14,017)
Other adjustments	(904)	(2,429)
Ending Balance	0	3,828	13,477
Severance and Related Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	1,304	4,006	368
Additions	0	9,357	14,614
Cash payments	(1,304)	(12,059)	(10,976)
Other adjustments	0	0
Ending Balance	0	1,304	4,006
Other Restructuring Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	2,524	9,471	6,036
Additions	1,859	2,186	6,476
Cash payments	(3,479)	(6,704)	(3,041)
Other adjustments	(904)	(2,429)
Ending Balance	$ 0	$ 2,524	$ 9,471

Separate Financial Informatio91

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Additional Information (Details)	Dec. 31, 2017
Guarantees [Member]
Guarantee Obligations [Line Items]
Percentage of voting stock outstanding in subsidiary guarantors	100.00%

Separate Financial Informatio92

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Supplemental Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 41,890		$ 48,236	$ 30,022	$ 7,123
Receivables, net	331,094		334,248
Assets held for sale, current		$ 2,000	20,242
Other current assets	19,681		30,404
Total current assets	392,665		433,130
Property, plant and equipment, net	44,006		46,547
Goodwill	1,071,371		1,078,454	1,093,178
Identifiable intangible assets, net	361,410		393,891
Deferred tax assets	150,535		232,283
Assets held for sale			11,962
Other assets	6,021		2,292
Total assets	2,026,008		2,198,559
Current liabilities:
Current portion of long-term debt	26,947		26,947
Accounts payable, trade	52,954		43,943
Accrued employment costs	77,545		98,860
Accrued expenses	74,856		76,870
Advance payments and billings in excess of costs incurred	30,380		33,259
Income tax liabilities	548		209
Liabilities held for sale, current			4,341
Other current liabilities	26,688		36,410
Total current liabilities	289,918		320,839
Long-term debt	938,687		1,039,993
Income tax liabilities	62,219		64,852
Liabilities held for sale			1,084
Other liabilities	59,079		66,986
Total liabilities	1,349,903		1,493,754
Shareholders' equity	676,105		704,805	706,133	476,753
Total liabilities and equity	2,026,008		2,198,559
Engility Holdings, Inc. [Member]
Current assets:
Investment in subsidiaries	676,105		704,805
Total assets	676,105		704,805
Current liabilities:
Shareholders' equity	676,105		704,805
Total liabilities and equity	676,105		704,805
Engility Corporation [Member]
Current assets:
Cash and cash equivalents	31,966		31,144	18,313
Receivables, net	301,047		297,334
Intercompany receivables			124,741
Assets held for sale, current			2,332
Other current assets	17,300		27,437
Total current assets	350,313		482,988
Property, plant and equipment, net	43,933		46,413
Goodwill	1,071,371		1,078,454
Identifiable intangible assets, net	361,410		393,891
Deferred tax assets	150,535		236,457
Assets held for sale			1
Investment in subsidiaries	67,623		(60,902)
Other assets	5,976		2,292
Total assets	2,051,161		2,179,594
Current liabilities:
Current portion of long-term debt	26,947		26,947
Accounts payable, trade	52,826		43,848
Intercompany payable	35,807		758
Accrued employment costs	68,622		87,263
Accrued expenses	74,657		76,520
Advance payments and billings in excess of costs incurred	30,380		33,259
Income tax liabilities	320
Other current liabilities	25,512		34,398
Total current liabilities	315,071		302,993
Long-term debt	938,687		1,039,993
Income tax liabilities	62,219		64,852
Other liabilities	59,079		66,951
Total liabilities	1,375,056		1,474,789
Shareholders' equity	676,105		704,805
Total liabilities and equity	2,051,161		2,179,594
Subsidiary Guarantors [Member]
Current assets:
Cash and cash equivalents	36		365	29	3,127
Receivables, net	9,562		18,030
Intercompany receivables	28,069
Assets held for sale, current			17,910
Other current assets	(4)		506
Total current assets	37,663		36,811
Property, plant and equipment, net			3
Deferred tax assets			(4,174)
Assets held for sale			11,961
Investment in subsidiaries	31,876		29,248
Other assets	45
Total assets	69,584		73,849
Current liabilities:
Accounts payable, trade			37
Intercompany payable			124,741
Accrued employment costs	1,961		4,466
Liabilities held for sale, current			4,341
Other current liabilities			47
Total current liabilities	1,961		133,632
Liabilities held for sale			1,084
Other liabilities			35
Total liabilities	1,961		134,751
Shareholders' equity	67,623		(60,902)
Total liabilities and equity	69,584		73,849
Subsidiary Non-guarantors [Member]
Current assets:
Cash and cash equivalents	9,888		16,727	$ 11,680	$ 3,996
Receivables, net	20,485		18,884
Intercompany receivables	7,738		758
Other current assets	2,385		2,461
Total current assets	40,496		38,830
Property, plant and equipment, net	73		131
Total assets	40,569		38,961
Current liabilities:
Accounts payable, trade	128		58
Accrued employment costs	6,962		7,131
Accrued expenses	199		350
Income tax liabilities	228		230
Other current liabilities	1,176		1,944
Total current liabilities	8,693		9,713
Total liabilities	8,693		9,713
Shareholders' equity	31,876		29,248
Total liabilities and equity	40,569		38,961
Consolidating Adjustments [Member]
Current assets:
Intercompany receivables	(35,807)		(125,499)
Total current assets	(35,807)		(125,499)
Investment in subsidiaries	(775,604)		(673,151)
Total assets	(811,411)		(798,650)
Current liabilities:
Intercompany payable	(35,807)		(125,499)
Income tax liabilities			(21)
Other current liabilities			21
Total current liabilities	(35,807)		(125,499)
Total liabilities	(35,807)		(125,499)
Shareholders' equity	(775,604)		(673,151)
Total liabilities and equity	$ (811,411)		$ (798,650)

Separate Financial Informatio93

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Details) - USD ($)	Nov. 30, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue			$ 1,931,887,000	$ 2,076,423,000	$ 2,085,623,000
Costs and expenses
Cost of revenue			1,655,729,000	1,777,844,000	1,779,709,000
Selling, general and administrative expenses			142,391,000	166,238,000	203,262,000
Goodwill impairment	$ 0	$ 292,000,000	7,083,000	9,875,000	292,100,000
Total costs and expenses			1,805,203,000	1,953,957,000	2,275,071,000
Operating income (loss)			126,684,000	122,466,000	(189,448,000)
Interest expense, net			76,716,000	131,185,000	110,143,000
Other expenses (income), net			227,000	80,000	(1,285,000)
Income (loss) before provision for income taxes			49,741,000	(8,799,000)	(298,306,000)
Provision (benefit) for income taxes			80,356,000	(2,730,000)	(68,067,000)
Net loss			(30,615,000)	(6,069,000)	(230,239,000)
Less: Net income attributable to non-controlling interest			4,576,000	4,738,000	5,113,000
Net loss attributable to Engility			(35,191,000)	(10,807,000)	(235,352,000)
Net loss			(30,615,000)	(6,069,000)	(230,239,000)
Other comprehensive income			1,060,000	2,364,000	1,789,000
Comprehensive loss			(29,555,000)	(3,705,000)	(228,450,000)
Less: Net income attributable to non-controlling interest			4,576,000	4,738,000	5,113,000
Comprehensive loss attributable to Engility			(34,131,000)	(8,443,000)	(233,563,000)
Engility Holdings, Inc. [Member]
Costs and expenses
Income (loss) in equity investments in subsidiaries			(35,191,000)	(10,807,000)	(235,352,000)
Income (loss) before provision for income taxes			(35,191,000)	(10,807,000)	(235,352,000)
Net loss			(35,191,000)	(10,807,000)	(235,352,000)
Net loss attributable to Engility			(35,191,000)	(10,807,000)	(235,352,000)
Net loss			(35,191,000)	(10,807,000)	(235,352,000)
Comprehensive loss			(35,191,000)	(10,807,000)	(235,352,000)
Comprehensive loss attributable to Engility			(35,191,000)	(10,807,000)	(235,352,000)
Engility Corporation [Member]
Revenue			1,755,936,000	1,834,718,000	1,796,441,000
Costs and expenses
Cost of revenue			1,470,400,000	1,503,356,000	1,519,802,000
Selling, general and administrative expenses			134,670,000	145,215,000	184,397,000
Goodwill impairment			7,083,000	9,875,000	292,100,000
Total costs and expenses			1,612,153,000	1,658,446,000	1,996,299,000
Operating income (loss)			143,783,000	176,272,000	(199,858,000)
Interest expense, net			76,716,000	131,185,000	110,148,000
Other expenses (income), net			(17,000)	(135,000)	(1,289,000)
Income (loss) in equity investments in subsidiaries			(21,920,000)	(58,753,000)	3,018,000
Income (loss) before provision for income taxes			45,164,000	(13,531,000)	(305,699,000)
Provision (benefit) for income taxes			80,355,000	(2,724,000)	(70,347,000)
Net loss			(35,191,000)	(10,807,000)	(235,352,000)
Net loss attributable to Engility			(35,191,000)	(10,807,000)	(235,352,000)
Net loss			(35,191,000)	(10,807,000)	(235,352,000)
Other comprehensive income			1,060,000	2,364,000	1,789,000
Comprehensive loss			(34,131,000)	(8,443,000)	(233,563,000)
Comprehensive loss attributable to Engility			(34,131,000)	(8,443,000)	(233,563,000)
Subsidiary Guarantors [Member]
Revenue			32,519,000	87,539,000	151,514,000
Costs and expenses
Cost of revenue			56,340,000	133,307,000	135,985,000
Selling, general and administrative expenses			3,287,000	17,964,000	15,162,000
Total costs and expenses			59,627,000	151,271,000	151,147,000
Operating income (loss)			(27,108,000)	(63,732,000)	367,000
Other expenses (income), net			(4,000)	1,000	4,000
Income (loss) in equity investments in subsidiaries			5,185,000	4,974,000	4,935,000
Income (loss) before provision for income taxes			(21,919,000)	(58,759,000)	5,298,000
Provision (benefit) for income taxes			1,000	(6,000)	2,280,000
Net loss			(21,920,000)	(58,753,000)	3,018,000
Net loss attributable to Engility			(21,920,000)	(58,753,000)	3,018,000
Net loss			(21,920,000)	(58,753,000)	3,018,000
Comprehensive loss			(21,920,000)	(58,753,000)	3,018,000
Comprehensive loss attributable to Engility			(21,920,000)	(58,753,000)	3,018,000
Subsidiary Non-guarantors [Member]
Revenue			143,432,000	154,166,000	156,704,000
Costs and expenses
Cost of revenue			128,989,000	141,181,000	142,958,000
Selling, general and administrative expenses			4,434,000	3,059,000	3,703,000
Total costs and expenses			133,423,000	144,240,000	146,661,000
Operating income (loss)			10,009,000	9,926,000	10,043,000
Interest expense, net					(5,000)
Other expenses (income), net			248,000	214,000
Income (loss) before provision for income taxes			9,761,000	9,712,000	10,048,000
Net loss			9,761,000	9,712,000	10,048,000
Less: Net income attributable to non-controlling interest			4,576,000	4,738,000	5,113,000
Net loss attributable to Engility			5,185,000	4,974,000	4,935,000
Net loss			9,761,000	9,712,000	10,048,000
Comprehensive loss			9,761,000	9,712,000	10,048,000
Less: Net income attributable to non-controlling interest			4,576,000	4,738,000	5,113,000
Comprehensive loss attributable to Engility			5,185,000	4,974,000	4,935,000
Consolidating Adjustments [Member]
Revenue					(19,036,000)
Costs and expenses
Cost of revenue					(19,036,000)
Total costs and expenses					(19,036,000)
Income (loss) in equity investments in subsidiaries			51,926,000	64,586,000	227,399,000
Income (loss) before provision for income taxes			51,926,000	64,586,000	227,399,000
Net loss			51,926,000	64,586,000	227,399,000
Net loss attributable to Engility			51,926,000	64,586,000	227,399,000
Net loss			51,926,000	64,586,000	227,399,000
Comprehensive loss			51,926,000	64,586,000	227,399,000
Comprehensive loss attributable to Engility			$ 51,926,000	$ 64,586,000	$ 227,399,000

Separate Financial Informatio94

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Supplemental Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	Aug. 12, 2016	Feb. 26, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Net cash provided by (used in) operating activities			$ 97,673	$ 94,405	$ 53,948
Investing activities:
Proceeds from sale of business, net of amount placed in escrow			22,349
Proceeds from sale of property, plant and equipment			2,902
Acquisitions, net of cash acquired					25,478
Capital expenditures			(9,691)	(21,446)	(19,610)
Net cash provided by (used in) investing activities			15,560	(21,446)	5,868
Financing activities:
Gross borrowings from issuance of long-term debt	$ 585			1,180,000	585,000
Repayment of long-term debt			(110,447)	(1,215,754)	(403,674)
Gross borrowings from revolving credit facility			318,500	137,000	157,000
Repayments of revolving credit facility			(318,500)	(137,000)	(115,000)
Debt issuance costs				(9,988)	(42,425)
Equity issuance costs					(2,590)
Proceeds from share-based payment arrangements				214	279
Payment of employee withholding taxes on share-based compensation			(1,501)	(1,779)	(8,021)
Dividends paid		$ (204,000)	(407)	(1,709)	(204,304)
Distributions to non-controlling interest member			(7,133)	(3,865)	(3,182)
Net cash used in financing activities			(119,488)	(52,881)	(36,917)
Change in cash from assets held from sale			(91)	(1,864)
Net change in cash and cash equivalents			(6,346)	18,214	22,899
Cash and cash equivalents, beginning of period			48,236	30,022	7,123
Cash and cash equivalents, end of period			41,890	48,236	30,022
Engility Holdings, Inc. [Member]
Operating activities:
Net cash provided by (used in) operating activities					5,530
Financing activities:
Equity issuance costs					(2,590)
Proceeds from share-based payment arrangements				214	279
Payment of employee withholding taxes on share-based compensation			(1,501)	(1,779)	(8,021)
Dividends paid			(407)	(1,709)	(204,304)
Due (to) from subsidiaries			1,908	3,274	209,106
Net cash used in financing activities					(5,530)
Engility Corporation [Member]
Operating activities:
Net cash provided by (used in) operating activities			(62,082)	163,949	85,842
Investing activities:
Proceeds from sale of business, net of amount placed in escrow			22,349
Proceeds from sale of property, plant and equipment			2,902
Acquisitions, net of cash acquired					25,478
Capital expenditures			(9,691)	(21,446)	(19,610)
Net cash provided by (used in) investing activities			15,560	(21,446)	5,868
Financing activities:
Gross borrowings from issuance of long-term debt				1,180,000	585,000
Repayment of long-term debt			(110,447)	(1,215,754)	(403,674)
Gross borrowings from revolving credit facility			318,500	137,000	157,000
Repayments of revolving credit facility			(318,500)	(137,000)	(115,000)
Debt issuance costs				(9,988)	(42,425)
Due (to) from subsidiaries			157,882	(82,066)	(254,298)
Net cash used in financing activities			47,435	(127,808)	(73,397)
Change in cash from assets held from sale			(91)	(1,864)
Net change in cash and cash equivalents			822	12,831	18,313
Cash and cash equivalents, beginning of period			31,144	18,313
Cash and cash equivalents, end of period			31,966	31,144	18,313
Subsidiary Guarantors [Member]
Operating activities:
Net cash provided by (used in) operating activities			152,481	(82,167)	(50,963)
Financing activities:
Due (to) from subsidiaries			(152,810)	82,503	47,865
Net cash used in financing activities			(152,810)	82,503	47,865
Net change in cash and cash equivalents			(329)	336	(3,098)
Cash and cash equivalents, beginning of period			365	29	3,127
Cash and cash equivalents, end of period			36	365	29
Subsidiary Non-guarantors [Member]
Operating activities:
Net cash provided by (used in) operating activities			7,274	12,623	13,539
Financing activities:
Distributions to non-controlling interest member			(7,133)	(3,865)	(3,182)
Due (to) from subsidiaries			(6,980)	(3,711)	(2,673)
Net cash used in financing activities			(14,113)	(7,576)	(5,855)
Net change in cash and cash equivalents			(6,839)	5,047	7,684
Cash and cash equivalents, beginning of period			16,727	11,680	3,996
Cash and cash equivalents, end of period			$ 9,888	$ 16,727	$ 11,680