Engility 10-Q 2 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 29, 2017	Oct. 27, 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-Q
Document Period End Date	Sep. 29, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	EGL
Amendment Flag	false
Entity Common Stock, Shares Outstanding (in shares)		36,824,915

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 51,978	$ 48,236
Receivables, net	341,713	334,248
Assets held for sale, current		20,242
Other current assets	22,754	30,404
Total current assets	416,445	433,130
Property, plant and equipment, net	44,428	46,547
Goodwill	1,078,454	1,078,454
Identifiable intangible assets, net	369,528	393,891
Deferred tax assets	216,234	232,283
Assets held for sale		11,962
Other assets	4,440	2,292
Total assets	2,129,529	2,198,559
Current liabilities:
Current portion of long-term debt	26,947	26,947
Accounts payable, trade	50,413	43,943
Accrued employment costs	96,727	98,860
Accrued expenses	81,965	76,870
Advance payments and billings in excess of costs incurred	31,905	33,259
Deferred income taxes, current and income tax liabilities	518	209
Liabilities held for sale, current		4,341
Other current liabilities	22,396	36,410
Total current liabilities	310,871	320,839
Long-term debt	960,499	1,039,993
Income tax liabilities	63,167	64,852
Liabilities held for sale		1,084
Other liabilities	62,839	66,986
Total liabilities	1,397,376	1,493,754
Commitments and contingencies (Note 10)
Equity:
Preferred stock, par value $0.01 per share, 25,000 shares authorized, none issued or outstanding as of September 29, 2017 or December 31, 2016
Common stock, par value $0.01 per share, 175,000 shares authorized, 36,825 and 36,776 shares issued and outstanding as of September 29, 2017 and December 31, 2016, respectively	368	368
Additional paid-in capital	1,243,023	1,237,826
Accumulated deficit	(516,459)	(541,702)
Accumulated other comprehensive loss	(5,504)	(4,865)
Non-controlling interest	10,725	13,178
Total equity	732,153	704,805
Total liabilities and equity	$ 2,129,529	$ 2,198,559

Unaudited Consolidated Balance3

Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 29, 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)	36,825,000	36,776,000
Common stock, shares outstanding (shares)	36,825,000	36,776,000

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue	$ 487,144	$ 511,800	$ 1,467,030	$ 1,570,011
Costs and expenses
Cost of revenue	417,581	435,594	1,255,603	1,341,826
Selling, general and administrative expenses	33,308	39,337	107,303	129,780
Total costs and expenses	450,889	474,931	1,362,906	1,471,606
Operating income	36,255	36,869	104,124	98,405
Interest expense, net	19,739	50,855	59,189	109,358
Other expenses, net	49		212	82
Income (loss) before provision for income taxes	16,467	(13,986)	44,723	(11,035)
Provision for income taxes	5,611	1,348	16,671	2,370
Net income (loss)	10,856	(15,334)	28,052	(13,405)
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Net income (loss) attributable to Engility	$ 9,805	$ (16,757)	$ 24,369	$ (17,493)
Earnings (loss) per share attributable to Engility
Basic	$ 0.27	$ (0.46)	$ 0.66	$ (0.48)
Diluted	$ 0.26	$ (0.46)	$ 0.65	$ (0.48)
Weighted average number of shares outstanding
Basic	36,809	36,735	36,831	36,726
Diluted	37,348	36,735	37,354	36,726

Unaudited Consolidated Stateme5

Unaudited Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 10,856	$ (15,334)	$ 28,052	$ (13,405)
Other comprehensive income (loss), net of tax:
Pension liability adjustment, net of tax benefit of $7 and $84 for the three and nine months ended September 29, 2017, respectively, and net of tax expense of $253 for the nine months ended September 30, 2016	(11)		(103)	632
Unrealized gain (loss) on derivative instruments, net of tax benefit of $28 and $343 for the three and nine months ended September 29, 2017, respectively, and net of tax expense of $334 and $1,084 for the three and nine months ended September 30, 2016, respectively	(44)	523	(536)	1,699
Other comprehensive income (loss), net of tax	(55)	523	(639)	2,331
Comprehensive income (loss)	10,801	(14,811)	27,413	(11,074)
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Comprehensive income (loss) attributable to Engility	$ 9,750	$ (16,234)	$ 23,730	$ (15,162)

Unaudited Consolidated Stateme6

Unaudited Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Pension liability adjustment, tax expense (benefit)	$ 7		$ 84	$ (253)
Unrealized gain (loss) on derivative instruments, tax expense (benefit)	$ (28)	$ 334	$ (343)	$ 1,084

Unaudited Consolidated Stateme7

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Operating activities:
Net income (loss)	$ 28,052	$ (13,405)
Share-based compensation	6,052	7,073
Depreciation and amortization	33,172	35,951
Loss (gain) on sale of property, plant and equipment	(306)	52
Loss on extinguishment of debt	432	4,642
Amortization of bank debt fees	6,484	3,428
Deferred income taxes	17,096	4,190
Excess tax deduction on share-based compensation	(191)
Changes in operating assets and liabilities:
Receivables	(7,465)	26,486
Other assets	7,894	(3,296)
Accounts payable, trade	5,332	2,777
Accrued employment costs	(2,133)	30,413
Accrued expenses	5,093	(5,930)
Advance payments and billings in excess of costs incurred	(1,354)	(12,372)
Other liabilities	(19,403)	4,735
Net cash provided by operating activities	78,755	84,744
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
Capital expenditures	(5,810)	(17,942)
Net cash provided by (used in) investing activities	19,441	(17,942)
Financing activities:
Gross borrowings from issuance of long-term debt		1,180,000
Repayment of long-term debt	(86,410)	(1,199,018)
Gross borrowings from revolving credit facility	270,000	73,000
Gross repayments of revolving credit facility	(270,000)	(73,000)
Debt issuance costs		(9,988)
Proceeds from share-based payment arrangements		214
Payment of employee withholding taxes on share-based compensation	(1,501)	(1,777)
Dividends paid	(407)	(1,703)
Distributions to non-controlling interest member	(6,136)	(3,865)
Net cash used in financing activities	(94,454)	(36,137)
Net change in cash and cash equivalents	3,742	30,665
Cash and cash equivalents, beginning of period	48,236	30,022
Cash and cash equivalents, end of period	$ 51,978	$ 60,687

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 29, 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 over six decades. 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 National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), and National Aeronautical and Space Administration (NASA). 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. We offer a broad range of services, including specialized technical consulting, program and business support, engineering and technology lifecycle support, information technology modernization and sustainment, supply chain services and logistics management and training and education to the U.S. government worldwide. Engility has no operations other than owning 100% of the capital stock of Engility Corporation (formerly TASC, Inc.), a Massachusetts 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. Principles of Consolidation and Basis of Presentation: The Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and in accordance with Article 10 of Regulation S-X of the U.S. Securities and Exchange Commission (SEC), and reflect the financial position, results of operations and cash flows of our businesses. Accordingly, they do not include all of the disclosures required by U.S. GAAP for a complete set of annual audited financial statements. All significant intercompany accounts and transactions are eliminated in consolidation. The Unaudited Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in our Annual Report on Form 10-K filed with the SEC on March 9, 2017 for the year ended December 31, 2016 (2016 Form 10-K). In the opinion of management, all adjustments (consisting of normal and recurring adjustments) considered necessary for a fair statement of the results for the interim periods presented have been included. Non-controlling Interest: Engility holds a 50.1% majority interest in Forfeiture Support Associates, LLC (FSA). The results of operations of FSA are included in Engility’s Unaudited Consolidated Financial Statements. The non-controlling interest reported on the Unaudited 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 U.S. 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 include revenue and profit recognition for contracts accounted on a percentage-of-completion basis, the recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income taxes and contingencies. Actual results experienced by the Company may differ materially from management's estimates. Reporting Periods: Our fiscal year begins on January 1 and ends on December 31. Our 2017 fiscal quarters end on March 31, June 30, September 29 and December 31. Our 2016 fiscal quarters ended on April 1, July 1, September 30 and December 31. 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 the nine months ended September 29, 2017 and September 30, 2016 were immaterial. For the three months ended September 29, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $4 million, of which $1 million was directly related to favorable performance on contract award fees. For the nine months ended September 29, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $9 million, of which $2 million was directly related to favorable performance on contract award fees. Amounts related to changes in estimates at completion for the three months ended September 30, 2016 represented a net increase to revenue and operating income of $5 million, of which $1 million was directly related to favorable performance on contract award fees. Amounts related to changes in estimates at completion for the nine months ended September 30, 2016 represented a net increase to revenue and operating income of $13 million, of which $3 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 September 29, 2017 and December 31, 2016, these receivables were approximately $10 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. The associated costs are deferred in other current assets in the accompanying consolidated balance sheets until funds are appropriated. Income Taxes: As of September 29, 2017, management has determined it is more likely than not a portion of state deferred tax assets, charitable donations, and foreign tax credits will not be realized and has recorded a valuation allowance against them. A change in the ability of our operations to continue to generate future taxable income could affect our ability to realize the future tax deductions underlying our deferred tax assets, and require us to provide a valuation allowance against our deferred tax assets. The recognition of a valuation allowance would result in a reduction to net income and, if significant, could have a material impact on our effective tax rate, results of operations and financial position in any given period. Earnings per Share: Basic earnings per share (EPS) is computed by dividing net income (loss) attributable to Engility by the weighted average number of common shares 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 (RSUs), stock options, performance shares, performance retention awards and performance units calculated using the treasury stock method. For the nine months ended September 29, 2017, 10,949 shares were excluded from diluted EPS due to their anti-dilutive effects. No shares were excluded from diluted EPS for the three months ended September 29, 2017. For the three and nine months ended September 30, 2016, 866,132 shares and 706,166 shares, respectively, were excluded from diluted EPS due to their anti-dilutive effects. The calculation of basic and diluted EPS are presented in the table below (shares in thousands). Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Net income (loss) attributable to Engility $ 9,805 $ (16,757 ) $ 24,369 $ (17,493 ) Weighted average number of shares outstanding – Basic 36,809 36,735 36,831 36,726 Dilutive effect of share-based compensation outstanding after application of the treasury stock method 539 — 523 — Weighted average number of shares outstanding – Diluted 37,348 36,735 37,354 36,726 Earnings (loss) per share attributable to Engility Basic $ 0.27 $ (0.46 ) $ 0.66 $ (0.48 ) Diluted $ 0.26 $ (0.46 ) $ 0.65 $ (0.48 ) Assets 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 working capital adjustments, that have not yet been finalized with the buyer. During the three months ended September 29, 2017, a cash adjustment of $1 million was recorded which reduced the purchase price. 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 received the proceeds from this sale, less an indemnity escrow of approximately $2 million, in the first quarter of 2017, which was used 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. 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 Company recorded a gain on sale of approximately $1 million which was recorded in selling, general and administrative expenses in the accompanying unaudited consolidated statement of operations.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 29, 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 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 (Topic 606) Principal versus Agent Considerations (Reporting Revenue Gross Versus Net) , Identifying Performance Obligations and Licensing Revenue from Contracts with Customers – Narrow Scope Improvements and Practical Expedients Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers

Receivables

Receivables	9 Months Ended
	Sep. 29, 2017
Receivables [Abstract]
Receivables	3. Receivables Our receivables principally relate to contracts with the U.S. government and prime contractors or subcontractors of the U.S. government. The components of contract receivables are presented in the table below. September 29, December 31, 2017 2016 Billed receivables $ 102,255 $ 97,661 Unbilled receivables 250,764 248,253 Allowance for doubtful accounts (11,306 ) (11,666 ) Total receivables, net $ 341,713 $ 334,248

Identifiable Intangible Assets

Identifiable Intangible Assets	9 Months Ended
	Sep. 29, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Identifiable Intangible Assets	4. Identifiable Intangible Assets Information on our identifiable intangible assets that are subject to amortization is presented in the table below. September 29, 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 $ 181,495 $ 363,734 $ 545,229 $ 157,482 $ 387,747 Technology 15 7,000 1,206 5,794 7,000 856 6,144 Total $ 552,229 $ 182,701 $ 369,528 $ 552,229 $ 158,338 $ 393,891 Our amortization expense recorded for our identifiable intangible assets is presented in the table below. Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Amortization expense $ 8,121 $ 8,428 $ 24,363 $ 28,235

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 29, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	5. Share-Based Compensation For the Nine Months Ended September 29, 2017 Performance Units: During the nine months ended September 29, 2017, we granted a total of 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 are based on continued employment 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. Restricted Stock Units: During the nine months ended September 29, 2017, we granted a total of 220,194 RSUs to certain 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 over a term of three years from the grant date, with one-third of the award vesting on each anniversary of the grant date. During the nine months ended September 29, 2017, we granted 29,431 RSUs to our independent directors with a grant date fair value of $28.25 per unit, which cliff vest on the first anniversary of the grant date. The number of shares of our common stock that are ultimately vested are based on continued employment or service as a director, as applicable. The RSUs may be settled in cash or stock at the sole discretion of the Compensation Committee. For the Nine Months Ended September 30, 2016 Performance Units: During the nine months ended September 30, 2016, we granted 411,178 performance units at a target level of 100% (with the potential for the delivery of up to 822,356 shares at the maximum performance level) to certain employees with a grant date fair value of $19.33 per unit. Included in the total, 81,803 performance units were granted at target level of 100% (with the potential for the delivery of up to 163,606 shares of our common stock at the maximum performance level) to Lynn A. Dugle, our Chief Executive Officer, with a grant date fair value of $17.97 per unit. Performance units cliff vest after three years based on our performance at the end of a three-year period beginning January 1, 2016. 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 200% of the target grant amount. The vesting of performance units depends initially on the Company’s performance, as approved by the Compensation Committee of our Board of Directors, based on two metrics: revenue and operating cash flow. The performance units may be settled in cash or stock at the sole discretion of the Compensation Committee. Restricted Stock Units: During the nine months ended September 30, 2016, we granted 506,493 RSUs to certain employees with a grant date fair value of $18.70 per unit, of which 56,524 RSUs cliff vest on the second anniversary of the grant date, 175,852 RSUs cliff vest on the third anniversary of the grant date and 274,117 RSUs vest over a term of three years from the grant date, 25% on the first anniversary of the grant date, 25% on the second anniversary of the grant date and 50% on the third anniversary of the grant date. Included in the total, 104,619 RSUs were granted to Ms. Dugle with a grant date fair value of $17.97 per unit, of which 50,083 RSUs cliff vest on the second anniversary of the grant date and 54,536 RSUs vest over a term of three years from the grant date. During the nine months ended September 30, 2016, we granted 25,704 RSUs to certain of the non-management members of our Board of Directors with a grant date fair value of $23.34 per unit, which cliff vest on the first anniversary of the grant date. The RSUs may be settled in cash or stock at the sole discretion of the Compensation Committee.

Defined Benefit Plans

Defined Benefit Plans	9 Months Ended
	Sep. 29, 2017
Postemployment Benefits [Abstract]
Defined Benefit Plans	6. Defined Benefit Plans The components of net periodic benefit costs for the Company’s defined benefit plans are as follows: Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Service cost $ 206 $ 201 $ 617 $ 604 Interest cost on projected benefit obligation 748 753 2,245 2,258 Expected return on plan assets (954 ) (953 ) (2,862 ) (2,860 ) Net loss amortization 95 73 284 219 Net periodic benefit expense $ 95 $ 74 $ 284 $ 221 During the nine months ended September 29, 2017, the Company contributed approximately $3 million to fund the defined benefit plans.

Debt

Debt	9 Months Ended
	Sep. 29, 2017
Debt Disclosure [Abstract]
Debt	7. Debt 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 margins 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 margin 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 transaction is expected to lower the Company’s fiscal year 2017 interest expense by approximately $5 million after fees and expenses. In addition, the debt refinancing that we completed in August 2016 lowered our annualized interest expense by approximately $23 million at the time of the refinancing. 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 $35.0 million and a swingline commitment for swingline borrowings of up to $35.0 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, as amended, requires the Borrower 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. The consolidated first lien net leverage ratio, which we believe is our most restrictive covenant, 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 September 29, 2017, we were in compliance with all covenants under the 2016 Credit Facility, and our consolidated first lien net leverage ratio was 3.27:1.00. As of September 29, 2017 and December 31, 2016 the composition of our debt was as follows: September 29, December 31, 2017 2016 Term Loans $ 737,000 $ 823,300 8.875% Senior Notes due 2024 (the Notes) 300,000 300,000 Other 352 461 Total debt 1,037,352 1,123,761 Less: current portion of long-term debt (26,947 ) (26,947 ) Less: unamortized original issue discount costs and financing fees (49,906 ) (56,821 ) Long-term debt $ 960,499 $ 1,039,993 Our availability under the revolving portion of the 2016 Credit Facility was $163 million as of September 29, 2017, with $2 million outstanding under letters of credit. During the nine months ended September 29, 2017, we repaid a total of $86 million of debt under the 2016 Credit Facility, including the prepayment of $66 million of Term B2 Loan debt. During the nine months ended September 29, 2017 we incurred approximately $3 million in fees related to the repricing of term loan debt in 2017. During the three and nine months ended September 30, 2016, we incurred a $10 million early termination penalty, recorded a loss on extinguishment of debt of $5 million and incurred a termination fee related to the interest rate swap of $2 million. In addition, the Company expensed approximately $11 million of debt issuances costs that did not qualify for deferral. These amounts are reflected in interest expense, net in the Consolidated Statement of Operations. Our weighted average outstanding loan balance for the three months ended September 29, 2017 was $1,060 million which accrued interest at a weighted average borrowing rate of approximately 5.85%. Our weighted average outstanding loan balance for the nine months ended September 29, 2017 was $1,088 million, which accrued interest at a weighted average borrowing rate of approximately 5.97%. Our weighted average outstanding loan balance for the three months ended September 30, 2016 was $1,145 million which accrued interest at a weighted average borrowing rate of approximately 7.58%. Our weighted average outstanding loan balance for the nine months ended September 30, 2016 was $1,149 million, which accrued interest at a weighted average borrowing rate of approximately 8.61%. The carrying value of the Term Loans, excluding original issue discount, and Notes approximated their fair value at September 29, 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 U.S. GAAP hierarchy.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 29, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. Fair Value Measurements The Company enters into interest rate swap contracts to reduce its exposure to variability in cash flows relating to interest payments on a portion of its outstanding debt payments. These interest rate contracts are designated as cash flow hedges. The effective portion of the derivative’s gain or loss is initially reported in stockholders’ equity (as a component of accumulated other comprehensive income (loss)) and will 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 will be reported in earnings. The Company does not have any derivatives outstanding that are not designated as hedges. During the first quarter of 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% The following table presents our liabilities that are measured at fair value on a recurring basis: September 29, December 31, Balance Sheet Classification Fair 2017 2016 Interest rate swap liabilities Other current liabilities Level 2 $ (835 ) $ — Interest rate swap liabilities Other liabilities Level 2 $ (44 ) $ — 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. The Company has agreements with each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company’s default on the indebtedness. If the Company had breached any of these provisions at September 29, 2017, it could have been required to settle its obligations under the agreements at their termination value. As of September 29, 2017, the Company had not posted any collateral related to these agreements. In connection with refinancing the 2015 Credit Facility (as defined in Note 11 Contract received: Floating interest rate LIBOR (subject to minimum of 1.25%) Contract paid: Fixed interest rates 3.09% - 3.18%

Restructuring Costs

Restructuring Costs	9 Months Ended
	Sep. 29, 2017
Restructuring And Related Activities [Abstract]
Restructuring Costs	9. Restructuring Costs The activity and balance of the restructuring liability account were as follows: Severance and Related Costs Other Restructuring Costs Total 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 ) (3,323 ) (4,627 ) Balance as of September 29, 2017 $ — $ 1,060 $ 1,060 As of September 29, 2017 and December 31, 2016, the restructuring liabilities were recognized within other current liabilities in the accompanying unaudited consolidated balance sheets. During the nine months ended September 29, 2017, we incurred other restructuring costs related to lease termination fees. As of September 29, 2017, the remaining liability primarily consisted of the costs incurred in the nine months ended September 29, 2017 and will be paid out by the end of 2017. The expenses related to the restructuring activity were contained within the selling, general and administrative expenses in the accompanying unaudited consolidated statement of operations for the appropriate period.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 29, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Procurement Regulations: Most 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. In the ordinary course of business, we cooperate with the U.S. government on 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. We do not currently 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 suspension 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, which would have a materially adverse effect on our consolidated financial position, results of operations and cash flows. 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 and Other 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 for 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 our consolidated balance sheets. Amounts recoverable from insurance contracts or third parties are recorded as assets when realized. At December 31, 2016 and September 29, 2017, 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 we have recorded adequate provisions for our litigation matters. We review these provisions quarterly and adjust these provisions to reflect the effect of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 29, 2017
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The provision for income taxes for the three months ended September 29, 2017 was $6 million compared to $1 million for the three months ended September 30, 2016. The effective tax rate for the three months ended September 29, 2017 was 34.1% as compared to (9.6)% for the three months ended September 30, 2016. The increase in the provision for income taxes and the effective tax rate, which includes the effects of discrete items, was primarily due to the earnings impact from our joint venture relative to our overall increased earnings for the three months ended September 29, 2017 as compared to the three months ended September 30, 2016. The provision for income taxes for the nine months ended September 29, 2017 was $17 million compared to $2 million for the nine months ended September 30, 2016. The effective tax rate for the nine months ended September 29, 2017 was 37.3% as compared to (21.5)% for the nine months ended September 30, 2016. The increase in the provision for income taxes and the effective tax rate, which includes the effects of discrete items, was primarily due to increased earnings and the sale of IRG in the first quarter of 2017. The Company continues to benefit from tax attributes acquired with the acquisition of TASC, including net operating losses. These tax assets are expected to significantly reduce net cash tax payments through 2024.

Separate Financial Information

Separate Financial Information of Subsidiary Guarantor of Indebtedness	9 Months Ended
	Sep. 29, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Separate Financial Information of Subsidiary Guarantor of Indebtedness	12. 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 (as defined in Note 11 to our audited consolidated financial statements in our 2016 Form 10-K), 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. As a result and 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: UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 36,460 $ 126 $ 15,392 $ — $ 51,978 Receivables, net — 302,383 22,126 17,204 — 341,713 Intercompany receivables — 69,131 — 6,284 (75,415 ) — Other current assets — 20,603 402 1,749 — 22,754 Total current assets — 428,577 22,654 40,629 (75,415 ) 416,445 Property, plant and equipment, net — 38,004 6,346 78 — 44,428 Goodwill — 1,020,027 58,427 — — 1,078,454 Identifiable intangible assets, net — 337,076 32,452 — — 369,528 Deferred tax assets — 193,074 23,160 — — 216,234 Investment in subsidiaries 732,153 74,416 30,349 — (836,918 ) — Other assets — 4,395 45 — — 4,440 Total assets $ 732,153 $ 2,095,569 $ 173,433 $ 40,707 $ (912,333 ) $ 2,129,529 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 50,293 45 75 — 50,413 Intercompany payable — 6,284 69,131 — (75,415 ) — Accrued employment costs — 84,809 2,955 8,963 — 96,727 Accrued expenses — 81,593 — 372 — 81,965 Advance payments and billings in excess of costs incurred — 31,905 — — — 31,905 Deferred income taxes, current and income tax liabilities — 312 — 206 518 Other current liabilities — 21,643 11 742 22,396 Total current liabilities — 303,786 72,142 10,358 (75,415 ) 310,871 Long-term debt — 960,499 — — — 960,499 Income tax liabilities — 63,167 — — — 63,167 Other liabilities — 35,964 26,875 — — 62,839 Total liabilities — 1,363,416 99,017 10,358 (75,415 ) 1,397,376 Shareholders' equity 732,153 732,153 74,416 30,349 (836,918 ) 732,153 Total liabilities and equity $ 732,153 $ 2,095,569 $ 173,433 $ 40,707 $ (912,333 ) $ 2,129,529 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 $ — $ 31,124 $ 385 $ 16,727 $ — $ 48,236 Receivables, net — 280,709 34,655 18,884 — 334,248 Intercompany receivables — 83,739 — 758 (84,497 ) — Assets held for sale, current — 2,332 17,910 — — 20,242 Other current assets — 27,437 506 2,461 — 30,404 Total current assets — 425,341 53,456 38,830 (84,497 ) 433,130 Property, plant and equipment, net — 40,071 6,345 131 — 46,547 Goodwill — 1,020,027 58,427 — — 1,078,454 Identifiable intangible assets, net — 359,465 34,426 — — 393,891 Deferred tax assets — 213,296 18,987 — — 232,283 Assets held for sale — — 11,962 — — 11,962 Investment in subsidiaries 704,805 89,543 29,248 — (823,596 ) — Other assets — 2,292 — — — 2,292 Total assets $ 704,805 $ 2,150,035 $ 212,851 $ 38,961 $ (908,093 ) $ 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 83,739 — (84,497 ) — Accrued employment costs — 87,199 4,530 7,131 — 98,860 Accrued expenses — 76,520 — 350 — 76,870 Advance payments and billings in excess of costs incurred — 33,259 — — — 33,259 Deferred income taxes, current and 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 — 302,929 92,694 9,713 (84,497 ) 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 — 37,456 29,530 — — 66,986 Total liabilities — 1,445,230 123,308 9,713 (84,497 ) 1,493,754 Shareholders' equity 704,805 704,805 89,543 29,248 (823,596 ) 704,805 Total liabilities and equity $ 704,805 $ 2,150,035 $ 212,851 $ 38,961 $ (908,093 ) $ 2,198,559 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE THREE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 430,261 $ 22,199 $ 34,684 $ — $ 487,144 Costs and expenses Cost of revenue — 360,520 25,343 31,718 — 417,581 Selling, general and administrative expenses — 29,240 2,925 1,143 — 33,308 Total costs and expenses — 389,760 28,268 32,861 — 450,889 Operating income (loss) — 40,501 (6,069 ) 1,823 — 36,255 Interest expense, net — 19,739 — — — 19,739 Other expenses (income), net — (7 ) (1 ) 57 — 49 Income (loss) in equity investments in subsidiaries 9,805 (5,534 ) 715 — (4,986 ) — Income (loss) before income taxes 9,805 15,235 (5,353 ) 1,766 (4,986 ) 16,467 Provision for income taxes — 5,430 181 — — 5,611 Net income (loss) 9,805 9,805 (5,534 ) 1,766 (4,986 ) 10,856 Less: Net income attributable to non-controlling interest — — — 1,051 — 1,051 Net income (loss) attributable to Engility $ 9,805 $ 9,805 $ (5,534 ) $ 715 $ (4,986 ) $ 9,805 Net income (loss) $ 9,805 $ 9,805 $ (5,534 ) $ 1,766 $ (4,986 ) $ 10,856 Other comprehensive loss — (44 ) (11 ) — — (55 ) Comprehensive income (loss) 9,805 9,761 (5,545 ) 1,766 (4,986 ) 10,801 Less: Net income attributable to non-controlling interest — — — 1,051 — 1,051 Comprehensive income (loss) attributable to Engility $ 9,805 $ 9,761 $ (5,545 ) $ 715 $ (4,986 ) $ 9,750 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE THREE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 428,217 $ 45,689 $ 37,894 $ — $ 511,800 Costs and expenses Cost of revenue — 348,629 52,537 34,428 — 435,594 Selling, general and administrative expenses — 29,549 8,980 808 — 39,337 Total costs and expenses — 378,178 61,517 35,236 — 474,931 Operating income (loss) — 50,039 (15,828 ) 2,658 — 36,869 Interest expense, net — 50,855 — — — 50,855 Other expenses (income), net — (66 ) — 66 — — Income (loss) in equity investments in subsidiaries (16,757 ) (14,710 ) 1,169 — 30,298 — Income (loss) before income taxes (16,757 ) (15,460 ) (14,659 ) 2,592 30,298 (13,986 ) Provision for income taxes — 1,297 51 — — 1,348 Net income (loss) (16,757 ) (16,757 ) (14,710 ) 2,592 30,298 (15,334 ) Less: Net income attributable to non-controlling interest — — — 1,423 — 1,423 Net income (loss) attributable to Engility $ (16,757 ) $ (16,757 ) $ (14,710 ) $ 1,169 $ 30,298 $ (16,757 ) Net income (loss) $ (16,757 ) $ (16,757 ) $ (14,710 ) $ 2,592 $ 30,298 $ (15,334 ) Other comprehensive income — 523 — — — 523 Comprehensive income (loss) (16,757 ) (16,234 ) (14,710 ) 2,592 30,298 (14,811 ) Less: Net income attributable to non-controlling interest — — — 1,423 — 1,423 Comprehensive income (loss) attributable to Engility $ (16,757 ) $ (16,234 ) $ (14,710 ) $ 1,169 $ 30,298 $ (16,234 ) UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE NINE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,283,964 $ 75,596 $ 107,470 $ — $ 1,467,030 Costs and expenses Cost of revenue — 1,075,098 83,613 96,892 — 1,255,603 Selling, general and administrative expenses — 94,430 9,766 3,107 — 107,303 Total costs and expenses — 1,169,528 93,379 99,999 — 1,362,906 Operating income (loss) — 114,436 (17,783 ) 7,471 — 104,124 Interest expense, net — 59,189 — — — 59,189 Other expenses (income), net — (19 ) (3 ) 234 — 212 Income (loss) in equity investments in subsidiaries 24,369 (15,024 ) 3,554 — (12,899 ) — Income (loss) before income taxes 24,369 40,242 (14,226 ) 7,237 (12,899 ) 44,723 Provision for income taxes — 15,873 798 — — 16,671 Net income (loss) 24,369 24,369 (15,024 ) 7,237 (12,899 ) 28,052 Less: Net income attributable to non-controlling interest — — — 3,683 — 3,683 Net income (loss) attributable to Engility $ 24,369 $ 24,369 $ (15,024 ) $ 3,554 $ (12,899 ) $ 24,369 Net income (loss) $ 24,369 $ 24,369 $ (15,024 ) $ 7,237 $ (12,899 ) $ 28,052 Other comprehensive loss — (536 ) (103 ) — — (639 ) Comprehensive income (loss) 24,369 23,833 (15,127 ) 7,237 (12,899 ) 27,413 Less: Net income attributable to non-controlling interest — — — 3,683 — 3,683 Comprehensive income (loss) attributable to Engility $ 24,369 $ 23,833 $ (15,127 ) $ 3,554 $ (12,899 ) $ 23,730 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,303,403 $ 148,117 $ 118,491 $ — $ 1,570,011 Costs and expenses Cost of revenue — 1,068,725 165,385 107,716 — 1,341,826 Selling, general and administrative expenses — 103,581 23,873 2,326 — 129,780 Goodwill impairment — — — — — — Total costs and expenses — 1,172,306 189,258 110,042 — 1,471,606 Operating income (loss) — 131,097 (41,141 ) 8,449 — 98,405 Interest expense, net — 109,358 — — — 109,358 Other expenses (income), net — (99 ) — 181 — 82 Income (loss) in equity investments in subsidiaries (17,493 ) (40,289 ) 4,180 — 53,602 — Income (loss) before income taxes (17,493 ) (18,451 ) (36,961 ) 8,268 53,602 (11,035 ) Provision (benefit) for income taxes — (958 ) 3,328 — — 2,370 Net income (loss) (17,493 ) (17,493 ) (40,289 ) 8,268 53,602 (13,405 ) Less: Net income attributable to non-controlling interest — — — 4,088 — 4,088 Net income (loss) attributable to Engility $ (17,493 ) $ (17,493 ) $ (40,289 ) $ 4,180 $ 53,602 $ (17,493 ) Net income (loss) $ (17,493 ) $ (17,493 ) $ (40,289 ) $ 8,268 $ 53,602 $ (13,405 ) Other comprehensive income — 1,699 632 — — 2,331 Comprehensive income (loss) (17,493 ) (15,794 ) (39,657 ) 8,268 53,602 (11,074 ) Less: Net income attributable to non-controlling interest — — — 4,088 — 4,088 Comprehensive income (loss) attributable to Engility $ (17,493 ) $ (15,794 ) $ (39,657 ) $ 4,180 $ 53,602 $ (15,162 ) UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE NINE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by operating activities $ — $ 54,079 $ 14,349 $ 10,327 $ — $ 78,755 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 — (5,810 ) — — — (5,810 ) Net cash provided by investing activities — 19,441 — — — 19,441 Financing activities: Repayment of long-term debt — (86,410 ) — — — (86,410 ) Gross borrowings from revolving credit facility — 270,000 — — — 270,000 Repayments of revolving credit facility — (270,000 ) — — — (270,000 ) Payment of employee withholding taxes on share-based compensation (1,501 ) — — — — (1,501 ) Dividends paid (407 ) — — — — (407 ) Distributions to non-controlling interest member — — — (6,136 ) — (6,136 ) Due (to) from subsidiaries 1,908 18,226 (14,608 ) (5,526 ) — — Net cash used in financing activities — (68,184 ) (14,608 ) (11,662 ) — (94,454 ) Net change in cash and cash equivalents — 5,336 (259 ) (1,335 ) — 3,742 Cash and cash equivalents, beginning of period — 31,124 385 16,727 — 48,236 Cash and cash equivalents, end of period $ — $ 36,460 $ 126 $ 15,392 $ — $ 51,978 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ 137,046 $ (64,341 ) $ 12,039 $ — $ 84,744 Investing activities: Capital expenditures — (17,942 ) — — — (17,942 ) Net cash used in investing activities — (17,942 ) — — — (17,942 ) Financing activities: Gross borrowings from issuance of long-term debt — 1,180,000 — — — 1,180,000 Repayment of long-term debt — (1,199,018 ) — — — (1,199,018 ) Gross borrowings from revolving credit facility — 73,000 — — — 73,000 Repayments of revolving credit facility — (73,000 ) — — — (73,000 ) Debt issuance costs — (9,988 ) — — — (9,988 ) Proceeds from share-based payment arrangements 214 — — — — 214 Payment of employee withholding taxes on share- based compensation (1,777 ) — — — — (1,777 ) Dividends paid (1,703 ) — — — — (1,703 ) Distributions to non-controlling interest member — — — (3,865 ) — (3,865 ) Due (to) from subsidiaries 3,266 (65,578 ) 65,413 (3,101 ) — — Net cash provided by (used in) financing activities — (94,584 ) 65,413 (6,966 ) — (36,137 ) Net change in cash and cash equivalents — 24,520 1,072 5,073 — 30,665 Cash and cash equivalents, beginning of period — 18,313 29 11,680 — 30,022 Cash and cash equivalents, end of period $ — $ 42,833 $ 1,101 $ 16,753 $ — $ 60,687

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 29, 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 over six decades. 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 National Geospatial-Intelligence Agency (NGA), Defense Intelligence Agency (DIA), the National Reconnaissance Office (NRO), and National Aeronautical and Space Administration (NASA). 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. We offer a broad range of services, including specialized technical consulting, program and business support, engineering and technology lifecycle support, information technology modernization and sustainment, supply chain services and logistics management and training and education to the U.S. government worldwide. Engility has no operations other than owning 100% of the capital stock of Engility Corporation (formerly TASC, Inc.), a Massachusetts 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.
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation: The Unaudited Consolidated Financial Statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and in accordance with Article 10 of Regulation S-X of the U.S. Securities and Exchange Commission (SEC), and reflect the financial position, results of operations and cash flows of our businesses. Accordingly, they do not include all of the disclosures required by U.S. GAAP for a complete set of annual audited financial statements. All significant intercompany accounts and transactions are eliminated in consolidation. The Unaudited Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. The accompanying financial information should be read in conjunction with the consolidated financial statements and notes thereto contained in our Annual Report on Form 10-K filed with the SEC on March 9, 2017 for the year ended December 31, 2016 (2016 Form 10-K). In the opinion of management, all adjustments (consisting of normal and recurring adjustments) considered necessary for a fair statement of the results for the interim periods presented have been included.
Non-controlling Interest	Non-controlling Interest: Engility holds a 50.1% majority interest in Forfeiture Support Associates, LLC (FSA). The results of operations of FSA are included in Engility’s Unaudited Consolidated Financial Statements. The non-controlling interest reported on the Unaudited 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 U.S. 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 include revenue and profit recognition for contracts accounted on a percentage-of-completion basis, the recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income taxes and contingencies. Actual results experienced by the Company may differ materially from management's estimates.
Reporting Periods	Reporting Periods: Our fiscal year begins on January 1 and ends on December 31. Our 2017 fiscal quarters end on March 31, June 30, September 29 and December 31. Our 2016 fiscal quarters ended on April 1, July 1, September 30 and December 31.
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 the nine months ended September 29, 2017 and September 30, 2016 were immaterial. For the three months ended September 29, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $4 million, of which $1 million was directly related to favorable performance on contract award fees. For the nine months ended September 29, 2017, the recognized amounts related to changes in estimates at completion represented a net increase to revenue and operating income of $9 million, of which $2 million was directly related to favorable performance on contract award fees. Amounts related to changes in estimates at completion for the three months ended September 30, 2016 represented a net increase to revenue and operating income of $5 million, of which $1 million was directly related to favorable performance on contract award fees. Amounts related to changes in estimates at completion for the nine months ended September 30, 2016 represented a net increase to revenue and operating income of $13 million, of which $3 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 September 29, 2017 and December 31, 2016, these receivables were approximately $10 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. The associated costs are deferred in other current assets in the accompanying consolidated balance sheets until funds are appropriated.
Income Taxes	Income Taxes: As of September 29, 2017, management has determined it is more likely than not a portion of state deferred tax assets, charitable donations, and foreign tax credits will not be realized and has recorded a valuation allowance against them. A change in the ability of our operations to continue to generate future taxable income could affect our ability to realize the future tax deductions underlying our deferred tax assets, and require us to provide a valuation allowance against our deferred tax assets. The recognition of a valuation allowance would result in a reduction to net income and, if significant, could have a material impact on our effective tax rate, results of operations and financial position in any given period.
Earnings Per Share	Earnings per Share: Basic earnings per share (EPS) is computed by dividing net income (loss) attributable to Engility by the weighted average number of common shares 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 (RSUs), stock options, performance shares, performance retention awards and performance units calculated using the treasury stock method. For the nine months ended September 29, 2017, 10,949 shares were excluded from diluted EPS due to their anti-dilutive effects. No shares were excluded from diluted EPS for the three months ended September 29, 2017. For the three and nine months ended September 30, 2016, 866,132 shares and 706,166 shares, respectively, were excluded from diluted EPS due to their anti-dilutive effects. The calculation of basic and diluted EPS are presented in the table below (shares in thousands). Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Net income (loss) attributable to Engility $ 9,805 $ (16,757 ) $ 24,369 $ (17,493 ) Weighted average number of shares outstanding – Basic 36,809 36,735 36,831 36,726 Dilutive effect of share-based compensation outstanding after application of the treasury stock method 539 — 523 — Weighted average number of shares outstanding – Diluted 37,348 36,735 37,354 36,726 Earnings (loss) per share attributable to Engility Basic $ 0.27 $ (0.46 ) $ 0.66 $ (0.48 ) Diluted $ 0.26 $ (0.46 ) $ 0.65 $ (0.48 )
Assets Held for Sale	Assets 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 working capital adjustments, that have not yet been finalized with the buyer. During the three months ended September 29, 2017, a cash adjustment of $1 million was recorded which reduced the purchase price. 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 received the proceeds from this sale, less an indemnity escrow of approximately $2 million, in the first quarter of 2017, which was used 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. 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 Company recorded a gain on sale of approximately $1 million which was recorded in selling, general and administrative expenses in the accompanying unaudited consolidated statement of operations.
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 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 (Topic 606) Principal versus Agent Considerations (Reporting Revenue Gross Versus Net) , Identifying Performance Obligations and Licensing Revenue from Contracts with Customers – Narrow Scope Improvements and Practical Expedients Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers

Basis of Presentation (Tables)

Basis of Presentation (Tables)	9 Months Ended
	Sep. 29, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Calculation of Basic and Diluted EPS	The calculation of basic and diluted EPS are presented in the table below (shares in thousands). Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Net income (loss) attributable to Engility $ 9,805 $ (16,757 ) $ 24,369 $ (17,493 ) Weighted average number of shares outstanding – Basic 36,809 36,735 36,831 36,726 Dilutive effect of share-based compensation outstanding after application of the treasury stock method 539 — 523 — Weighted average number of shares outstanding – Diluted 37,348 36,735 37,354 36,726 Earnings (loss) per share attributable to Engility Basic $ 0.27 $ (0.46 ) $ 0.66 $ (0.48 ) Diluted $ 0.26 $ (0.46 ) $ 0.65 $ (0.48 )

Receivables (Tables)

Receivables (Tables)	9 Months Ended
	Sep. 29, 2017
Receivables [Abstract]
Components of Contract Receivables	Our receivables principally relate to contracts with the U.S. government and prime contractors or subcontractors of the U.S. government. The components of contract receivables are presented in the table below. September 29, December 31, 2017 2016 Billed receivables $ 102,255 $ 97,661 Unbilled receivables 250,764 248,253 Allowance for doubtful accounts (11,306 ) (11,666 ) Total receivables, net $ 341,713 $ 334,248

Identifiable Intangible Assets

Identifiable Intangible Assets (Tables)	9 Months Ended
	Sep. 29, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Information on Identifiable Intangible Assets	Information on our identifiable intangible assets that are subject to amortization is presented in the table below. September 29, 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 $ 181,495 $ 363,734 $ 545,229 $ 157,482 $ 387,747 Technology 15 7,000 1,206 5,794 7,000 856 6,144 Total $ 552,229 $ 182,701 $ 369,528 $ 552,229 $ 158,338 $ 393,891
Amortization Expense Recorded for Identifiable Intangible Assets	Our amortization expense recorded for our identifiable intangible assets is presented in the table below. Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Amortization expense $ 8,121 $ 8,428 $ 24,363 $ 28,235

Defined Benefit Plans (Tables)

Defined Benefit Plans (Tables)	9 Months Ended
	Sep. 29, 2017
Postemployment Benefits [Abstract]
Components of Net Periodic Benefit Costs for Defined Benefit Plans	The components of net periodic benefit costs for the Company’s defined benefit plans are as follows: Three Months Ended Nine Months Ended September 29, 2017 September 30, 2016 September 29, 2017 September 30, 2016 Service cost $ 206 $ 201 $ 617 $ 604 Interest cost on projected benefit obligation 748 753 2,245 2,258 Expected return on plan assets (954 ) (953 ) (2,862 ) (2,860 ) Net loss amortization 95 73 284 219 Net periodic benefit expense $ 95 $ 74 $ 284 $ 221

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 29, 2017
Debt Disclosure [Abstract]
Schedule of Composition of Debt	As of September 29, 2017 and December 31, 2016 the composition of our debt was as follows: September 29, December 31, 2017 2016 Term Loans $ 737,000 $ 823,300 8.875% Senior Notes due 2024 (the Notes) 300,000 300,000 Other 352 461 Total debt 1,037,352 1,123,761 Less: current portion of long-term debt (26,947 ) (26,947 ) Less: unamortized original issue discount costs and financing fees (49,906 ) (56,821 ) Long-term debt $ 960,499 $ 1,039,993

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 29, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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 liabilities that are measured at fair value on a recurring basis: September 29, December 31, Balance Sheet Classification Fair 2017 2016 Interest rate swap liabilities Other current liabilities Level 2 $ (835 ) $ — Interest rate swap liabilities Other liabilities Level 2 $ (44 ) $ —
Credit Facility 2015 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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 Costs (Tables)

Restructuring Costs (Tables)	9 Months Ended
	Sep. 29, 2017
Restructuring And Related Activities [Abstract]
Summary of Restructuring Cost	The activity and balance of the restructuring liability account were as follows: Severance and Related Costs Other Restructuring Costs Total 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 ) (3,323 ) (4,627 ) Balance as of September 29, 2017 $ — $ 1,060 $ 1,060

Separate Financial Informatio28

Separate Financial Information of Subsidiary Guarantor of Indebtedness (Tables)	9 Months Ended
	Sep. 29, 2017
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Unaudited Supplemental Condensed Consolidating Balance Sheet	UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING BALANCE SHEET AS OF SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Assets: Current assets: Cash and cash equivalents $ — $ 36,460 $ 126 $ 15,392 $ — $ 51,978 Receivables, net — 302,383 22,126 17,204 — 341,713 Intercompany receivables — 69,131 — 6,284 (75,415 ) — Other current assets — 20,603 402 1,749 — 22,754 Total current assets — 428,577 22,654 40,629 (75,415 ) 416,445 Property, plant and equipment, net — 38,004 6,346 78 — 44,428 Goodwill — 1,020,027 58,427 — — 1,078,454 Identifiable intangible assets, net — 337,076 32,452 — — 369,528 Deferred tax assets — 193,074 23,160 — — 216,234 Investment in subsidiaries 732,153 74,416 30,349 — (836,918 ) — Other assets — 4,395 45 — — 4,440 Total assets $ 732,153 $ 2,095,569 $ 173,433 $ 40,707 $ (912,333 ) $ 2,129,529 Liabilities and Equity: Current liabilities: Current portion of long-term debt $ — $ 26,947 $ — $ — $ — $ 26,947 Accounts payable, trade — 50,293 45 75 — 50,413 Intercompany payable — 6,284 69,131 — (75,415 ) — Accrued employment costs — 84,809 2,955 8,963 — 96,727 Accrued expenses — 81,593 — 372 — 81,965 Advance payments and billings in excess of costs incurred — 31,905 — — — 31,905 Deferred income taxes, current and income tax liabilities — 312 — 206 518 Other current liabilities — 21,643 11 742 22,396 Total current liabilities — 303,786 72,142 10,358 (75,415 ) 310,871 Long-term debt — 960,499 — — — 960,499 Income tax liabilities — 63,167 — — — 63,167 Other liabilities — 35,964 26,875 — — 62,839 Total liabilities — 1,363,416 99,017 10,358 (75,415 ) 1,397,376 Shareholders' equity 732,153 732,153 74,416 30,349 (836,918 ) 732,153 Total liabilities and equity $ 732,153 $ 2,095,569 $ 173,433 $ 40,707 $ (912,333 ) $ 2,129,529 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 $ — $ 31,124 $ 385 $ 16,727 $ — $ 48,236 Receivables, net — 280,709 34,655 18,884 — 334,248 Intercompany receivables — 83,739 — 758 (84,497 ) — Assets held for sale, current — 2,332 17,910 — — 20,242 Other current assets — 27,437 506 2,461 — 30,404 Total current assets — 425,341 53,456 38,830 (84,497 ) 433,130 Property, plant and equipment, net — 40,071 6,345 131 — 46,547 Goodwill — 1,020,027 58,427 — — 1,078,454 Identifiable intangible assets, net — 359,465 34,426 — — 393,891 Deferred tax assets — 213,296 18,987 — — 232,283 Assets held for sale — — 11,962 — — 11,962 Investment in subsidiaries 704,805 89,543 29,248 — (823,596 ) — Other assets — 2,292 — — — 2,292 Total assets $ 704,805 $ 2,150,035 $ 212,851 $ 38,961 $ (908,093 ) $ 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 83,739 — (84,497 ) — Accrued employment costs — 87,199 4,530 7,131 — 98,860 Accrued expenses — 76,520 — 350 — 76,870 Advance payments and billings in excess of costs incurred — 33,259 — — — 33,259 Deferred income taxes, current and 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 — 302,929 92,694 9,713 (84,497 ) 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 — 37,456 29,530 — — 66,986 Total liabilities — 1,445,230 123,308 9,713 (84,497 ) 1,493,754 Shareholders' equity 704,805 704,805 89,543 29,248 (823,596 ) 704,805 Total liabilities and equity $ 704,805 $ 2,150,035 $ 212,851 $ 38,961 $ (908,093 ) $ 2,198,559
Unaudited Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income (Loss)	UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE THREE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 430,261 $ 22,199 $ 34,684 $ — $ 487,144 Costs and expenses Cost of revenue — 360,520 25,343 31,718 — 417,581 Selling, general and administrative expenses — 29,240 2,925 1,143 — 33,308 Total costs and expenses — 389,760 28,268 32,861 — 450,889 Operating income (loss) — 40,501 (6,069 ) 1,823 — 36,255 Interest expense, net — 19,739 — — — 19,739 Other expenses (income), net — (7 ) (1 ) 57 — 49 Income (loss) in equity investments in subsidiaries 9,805 (5,534 ) 715 — (4,986 ) — Income (loss) before income taxes 9,805 15,235 (5,353 ) 1,766 (4,986 ) 16,467 Provision for income taxes — 5,430 181 — — 5,611 Net income (loss) 9,805 9,805 (5,534 ) 1,766 (4,986 ) 10,856 Less: Net income attributable to non-controlling interest — — — 1,051 — 1,051 Net income (loss) attributable to Engility $ 9,805 $ 9,805 $ (5,534 ) $ 715 $ (4,986 ) $ 9,805 Net income (loss) $ 9,805 $ 9,805 $ (5,534 ) $ 1,766 $ (4,986 ) $ 10,856 Other comprehensive loss — (44 ) (11 ) — — (55 ) Comprehensive income (loss) 9,805 9,761 (5,545 ) 1,766 (4,986 ) 10,801 Less: Net income attributable to non-controlling interest — — — 1,051 — 1,051 Comprehensive income (loss) attributable to Engility $ 9,805 $ 9,761 $ (5,545 ) $ 715 $ (4,986 ) $ 9,750 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE THREE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 428,217 $ 45,689 $ 37,894 $ — $ 511,800 Costs and expenses Cost of revenue — 348,629 52,537 34,428 — 435,594 Selling, general and administrative expenses — 29,549 8,980 808 — 39,337 Total costs and expenses — 378,178 61,517 35,236 — 474,931 Operating income (loss) — 50,039 (15,828 ) 2,658 — 36,869 Interest expense, net — 50,855 — — — 50,855 Other expenses (income), net — (66 ) — 66 — — Income (loss) in equity investments in subsidiaries (16,757 ) (14,710 ) 1,169 — 30,298 — Income (loss) before income taxes (16,757 ) (15,460 ) (14,659 ) 2,592 30,298 (13,986 ) Provision for income taxes — 1,297 51 — — 1,348 Net income (loss) (16,757 ) (16,757 ) (14,710 ) 2,592 30,298 (15,334 ) Less: Net income attributable to non-controlling interest — — — 1,423 — 1,423 Net income (loss) attributable to Engility $ (16,757 ) $ (16,757 ) $ (14,710 ) $ 1,169 $ 30,298 $ (16,757 ) Net income (loss) $ (16,757 ) $ (16,757 ) $ (14,710 ) $ 2,592 $ 30,298 $ (15,334 ) Other comprehensive income — 523 — — — 523 Comprehensive income (loss) (16,757 ) (16,234 ) (14,710 ) 2,592 30,298 (14,811 ) Less: Net income attributable to non-controlling interest — — — 1,423 — 1,423 Comprehensive income (loss) attributable to Engility $ (16,757 ) $ (16,234 ) $ (14,710 ) $ 1,169 $ 30,298 $ (16,234 ) UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE NINE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,283,964 $ 75,596 $ 107,470 $ — $ 1,467,030 Costs and expenses Cost of revenue — 1,075,098 83,613 96,892 — 1,255,603 Selling, general and administrative expenses — 94,430 9,766 3,107 — 107,303 Total costs and expenses — 1,169,528 93,379 99,999 — 1,362,906 Operating income (loss) — 114,436 (17,783 ) 7,471 — 104,124 Interest expense, net — 59,189 — — — 59,189 Other expenses (income), net — (19 ) (3 ) 234 — 212 Income (loss) in equity investments in subsidiaries 24,369 (15,024 ) 3,554 — (12,899 ) — Income (loss) before income taxes 24,369 40,242 (14,226 ) 7,237 (12,899 ) 44,723 Provision for income taxes — 15,873 798 — — 16,671 Net income (loss) 24,369 24,369 (15,024 ) 7,237 (12,899 ) 28,052 Less: Net income attributable to non-controlling interest — — — 3,683 — 3,683 Net income (loss) attributable to Engility $ 24,369 $ 24,369 $ (15,024 ) $ 3,554 $ (12,899 ) $ 24,369 Net income (loss) $ 24,369 $ 24,369 $ (15,024 ) $ 7,237 $ (12,899 ) $ 28,052 Other comprehensive loss — (536 ) (103 ) — — (639 ) Comprehensive income (loss) 24,369 23,833 (15,127 ) 7,237 (12,899 ) 27,413 Less: Net income attributable to non-controlling interest — — — 3,683 — 3,683 Comprehensive income (loss) attributable to Engility $ 24,369 $ 23,833 $ (15,127 ) $ 3,554 $ (12,899 ) $ 23,730 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Revenue $ — $ 1,303,403 $ 148,117 $ 118,491 $ — $ 1,570,011 Costs and expenses Cost of revenue — 1,068,725 165,385 107,716 — 1,341,826 Selling, general and administrative expenses — 103,581 23,873 2,326 — 129,780 Goodwill impairment — — — — — — Total costs and expenses — 1,172,306 189,258 110,042 — 1,471,606 Operating income (loss) — 131,097 (41,141 ) 8,449 — 98,405 Interest expense, net — 109,358 — — — 109,358 Other expenses (income), net — (99 ) — 181 — 82 Income (loss) in equity investments in subsidiaries (17,493 ) (40,289 ) 4,180 — 53,602 — Income (loss) before income taxes (17,493 ) (18,451 ) (36,961 ) 8,268 53,602 (11,035 ) Provision (benefit) for income taxes — (958 ) 3,328 — — 2,370 Net income (loss) (17,493 ) (17,493 ) (40,289 ) 8,268 53,602 (13,405 ) Less: Net income attributable to non-controlling interest — — — 4,088 — 4,088 Net income (loss) attributable to Engility $ (17,493 ) $ (17,493 ) $ (40,289 ) $ 4,180 $ 53,602 $ (17,493 ) Net income (loss) $ (17,493 ) $ (17,493 ) $ (40,289 ) $ 8,268 $ 53,602 $ (13,405 ) Other comprehensive income — 1,699 632 — — 2,331 Comprehensive income (loss) (17,493 ) (15,794 ) (39,657 ) 8,268 53,602 (11,074 ) Less: Net income attributable to non-controlling interest — — — 4,088 — 4,088 Comprehensive income (loss) attributable to Engility $ (17,493 ) $ (15,794 ) $ (39,657 ) $ 4,180 $ 53,602 $ (15,162 )
Unaudited Supplemental Condensed Consolidating Statement of Cash Flows	UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE NINE MONTHS ENDED SEPTEMBER 29, 2017 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by operating activities $ — $ 54,079 $ 14,349 $ 10,327 $ — $ 78,755 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 — (5,810 ) — — — (5,810 ) Net cash provided by investing activities — 19,441 — — — 19,441 Financing activities: Repayment of long-term debt — (86,410 ) — — — (86,410 ) Gross borrowings from revolving credit facility — 270,000 — — — 270,000 Repayments of revolving credit facility — (270,000 ) — — — (270,000 ) Payment of employee withholding taxes on share-based compensation (1,501 ) — — — — (1,501 ) Dividends paid (407 ) — — — — (407 ) Distributions to non-controlling interest member — — — (6,136 ) — (6,136 ) Due (to) from subsidiaries 1,908 18,226 (14,608 ) (5,526 ) — — Net cash used in financing activities — (68,184 ) (14,608 ) (11,662 ) — (94,454 ) Net change in cash and cash equivalents — 5,336 (259 ) (1,335 ) — 3,742 Cash and cash equivalents, beginning of period — 31,124 385 16,727 — 48,236 Cash and cash equivalents, end of period $ — $ 36,460 $ 126 $ 15,392 $ — $ 51,978 UNAUDITED SUPPLEMENTAL CONDENSED CONSOLIDATING STATEMENT OF CASH FLOWS FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2016 Engility Holdings, Inc. Engility Corporation Subsidiary Guarantors Subsidiary Non- guarantors Consolidating Adjustments Consolidated Operating activities: Net cash provided by (used in) operating activities $ — $ 137,046 $ (64,341 ) $ 12,039 $ — $ 84,744 Investing activities: Capital expenditures — (17,942 ) — — — (17,942 ) Net cash used in investing activities — (17,942 ) — — — (17,942 ) Financing activities: Gross borrowings from issuance of long-term debt — 1,180,000 — — — 1,180,000 Repayment of long-term debt — (1,199,018 ) — — — (1,199,018 ) Gross borrowings from revolving credit facility — 73,000 — — — 73,000 Repayments of revolving credit facility — (73,000 ) — — — (73,000 ) Debt issuance costs — (9,988 ) — — — (9,988 ) Proceeds from share-based payment arrangements 214 — — — — 214 Payment of employee withholding taxes on share- based compensation (1,777 ) — — — — (1,777 ) Dividends paid (1,703 ) — — — — (1,703 ) Distributions to non-controlling interest member — — — (3,865 ) — (3,865 ) Due (to) from subsidiaries 3,266 (65,578 ) 65,413 (3,101 ) — — Net cash provided by (used in) financing activities — (94,584 ) 65,413 (6,966 ) — (36,137 ) Net change in cash and cash equivalents — 24,520 1,072 5,073 — 30,665 Cash and cash equivalents, beginning of period — 18,313 29 11,680 — 30,022 Cash and cash equivalents, end of period $ — $ 42,833 $ 1,101 $ 16,753 $ — $ 60,687

Basis of Presentation - Additio

Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	Jan. 06, 2017	Sep. 29, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016	Dec. 31, 2016
Basis of Presentation [Line Items]
Unbilled receivables restructuring costs incurred		$ 10,000			$ 10,000		$ 11,000
Antidilutive securities		0		866,132	10,949	706,166
Sale of long-term assets			$ 2,000
Accumulated depreciation			1,000
Gain on sale of long-term assets					$ (306)	$ 52
Selling, General and Administrative Expenses [Member]
Basis of Presentation [Line Items]
Gain on sale of long-term assets			1,000
International Resources Group Ltd. [Member]
Basis of Presentation [Line Items]
Initial purchase price	$ 25,000
Cash adjustment reduce the purchase price		$ 1,000
Indemnity escrow			$ 2,000
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)		4,000		$ 5,000	9,000	13,000
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)		$ 1,000		$ 1,000	$ 2,000	$ 3,000
Engility Corporation [Member]
Basis of Presentation [Line Items]
Capital stock owning percentage by parent		100.00%			100.00%
Forfeiture Support Associates LLC [Member]
Basis of Presentation [Line Items]
Non-controlling equity interest ownership percentage		50.10%			50.10%

Basis of Presentation - Calcula

Basis of Presentation - Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net income (loss) attributable to Engility	$ 9,805	$ (16,757)	$ 24,369	$ (17,493)
Weighted average number of shares outstanding – Basic	36,809	36,735	36,831	36,726
Dilutive effect of share-based compensation outstanding after application of the treasury stock method	539		523
Weighted average number of shares outstanding – Diluted	37,348	36,735	37,354	36,726
Earnings (loss) per share attributable to Engility
Basic	$ 0.27	$ (0.46)	$ 0.66	$ (0.48)
Diluted	$ 0.26	$ (0.46)	$ 0.65	$ (0.48)

New Accounting Pronouncements -

New Accounting Pronouncements - Additional Information (Details) - USD ($)	3 Months Ended				9 Months Ended
	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	$ 5,611,000			$ 1,348,000	$ 16,671,000	$ 2,370,000
Excess tax benefits recognized as a reduction to tax expense					191,000
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)		$ 200,000	$ (400,000)
Cumulative effect on retained earnings, net of tax			$ 900,000
Excess tax benefits recognized as a reduction to tax expense					$ 200,000	$ 0

Receivables - Components of Con

Receivables - Components of Contract Receivables (Details) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2016
Receivables [Abstract]
Billed receivables	$ 102,255	$ 97,661
Unbilled receivables	250,764	248,253
Allowance for doubtful accounts	(11,306)	(11,666)
Total receivables, net	$ 341,713	$ 334,248

Identifiable Intangible Asset33

Identifiable Intangible Assets - Information on Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 552,229	$ 552,229
Accumulated Amortization	182,701	158,338
Net Carrying Amount	$ 369,528	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	181,495	157,482
Net Carrying Amount	$ 363,734	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	1,206	856
Net Carrying Amount	$ 5,794	$ 6,144

Identifiable Intangible Asset34

Identifiable Intangible Assets - Amortization Expense Recorded for Identifiable Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 8,121	$ 8,428	$ 24,363	$ 28,235

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - $ / shares	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Employees [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	189,351	411,178
Shares granted at maximum performance level	568,053	822,356
Weighted average share price (USD per share)	$ 30.54	$ 19.33
Performance period	3 years	3 years
Percent of the target grant amount	100.00%	100.00%
Employees [Member] | Performance Shares [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	0.00%	0.00%
Employees [Member] | Performance Shares [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	300.00%	200.00%
Employees [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	220,194	506,493
Weighted average share price (USD per share)	$ 30.44	$ 18.70
Vesting period	3 years	3 years
Employees [Member] | Restricted Stock Units (RSUs) [Member] | Period One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	775
Shares vested in period (in percentage)		25.00%
Employees [Member] | Restricted Stock Units (RSUs) [Member] | Period Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	12,137	56,524
Shares vested in period (in percentage)		25.00%
Employees [Member] | Restricted Stock Units (RSUs) [Member] | Over Period One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)	207,282	274,117
Employees [Member] | Restricted Stock Units (RSUs) [Member] | Period Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)		175,852
Shares vested in period (in percentage)	33.33%	50.00%
Non-management Members Of The Board Of Directors [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period	29,431	25,704
Weighted average share price (USD per share)	$ 28.25	$ 23.34
Chief Executive Officer [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		81,803
Shares granted at maximum performance level		163,606
Weighted average share price (USD per share)		$ 17.97
Performance period		3 years
Percent of the target grant amount		100.00%
Chief Executive Officer [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		104,619
Weighted average share price (USD per share)		$ 17.97
Vesting period		3 years
Chief Executive Officer [Member] | Restricted Stock Units (RSUs) [Member] | Period Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)		50,083
Chief Executive Officer [Member] | Restricted Stock Units (RSUs) [Member] | Over Period One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period (in shares)		54,536

Defined Benefit Plans - Compone

Defined Benefit Plans - Components of Net Periodic Benefit Costs for Defined Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Postemployment Benefits [Abstract]
Service cost	$ 206	$ 201	$ 617	$ 604
Interest cost on projected benefit obligation	748	753	2,245	2,258
Expected return on plan assets	(954)	(953)	(2,862)	(2,860)
Net loss amortization	95	73	284	219
Net periodic benefit expense	$ 95	$ 74	$ 284	$ 221

Defined Benefit Plans - Additio

Defined Benefit Plans - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 29, 2017USD ($)
Postemployment Benefits [Abstract]
Company contributed to defined benefit plans	$ 3

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Aug. 14, 2017	Feb. 13, 2017	Aug. 12, 2016	Aug. 30, 2016	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Repayment of term loan debt							$ 270,000,000	$ 73,000,000
Early termination penalty						$ 10,000,000		10,000,000
Loss on extinguishment of debt						(5,000,000)	(432,000)	(4,642,000)
Debt issuances costs						11,000,000		11,000,000
Average outstanding loan amount					$ 1,060,000,000	$ 1,145,000,000	$ 1,088,000,000	$ 1,149,000,000
Interest rate during period					5.85%	7.58%	5.97%	8.61%
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt						$ (2,000,000)		$ (2,000,000)
2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			$ 1,045,000,000
Secured debt To EBITDA ratio			6.125%
Consolidated net leverage ratio					3.27%		3.27%
Current borrowing capacity					$ 163,000,000		$ 163,000,000
Repayment of term loan debt							86,000,000
2016 Credit Facility [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit, amount outstanding					$ 2,000,000		2,000,000
First Amendment [Member]
Debt Instrument [Line Items]
Expected Interest expense, after fees and expenses in fiscal year 2017							5,000,000
Decrease in interest expense at the time of debt refinancing				$ 23,000,000
Term Loan [Member]
Debt Instrument [Line Items]
Early termination penalty							3,000,000
Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility		$ 195,000,000	$ 200,000,000
Term B2 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility		608,000,000	680,000,000
Prepayment of term loan debt							$ 66,000,000
Senior Secured Revolving Credit Facility [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Total credit facility			165,000,000
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
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] | New Term B1 Loans [Member] | Amendment Two [Member]
Debt Instrument [Line Items]
Additional borrowing capacity	$ 185,000,000
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] | Amendment Two [Member]
Debt Instrument [Line Items]
Additional borrowing capacity	$ 579,000,000
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] | Term B1 Loan [Member] | 2016 Credit Facility [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%	2.25%	3.25%
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%
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%

Debt - Schedule of Composition

Debt - Schedule of Composition of Debt (Details) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total debt	$ 1,037,352	$ 1,123,761
Less: current portion of long-term debt	(26,947)	(26,947)
Less: unamortized original issue discount costs and financing fees	(49,906)	(56,821)
Long-term debt	960,499	1,039,993
8.875% Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Total debt	300,000	300,000
Term Loan [Member]
Debt Instrument [Line Items]
Total debt	737,000	823,300
Other [Member]
Debt Instrument [Line Items]
Total debt	$ 352	$ 461

Debt - Schedule of Compositio40

Debt - Schedule of Composition of Debt (Parenthetical) (Details) - 8.875% Senior Notes Due 2024 [Member]	9 Months Ended	12 Months Ended
	Sep. 29, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Interest percentage	8.875%	8.875%
Maturity year	2,024	2,024

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount		$ 200
Derivative, expiration date	Dec. 31, 2020
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

Fair Value Measurements - Other

Fair Value Measurements - Other Terms of Instruments (Details) - Interest Rate Swap [Member]	Mar. 31, 2017	Sep. 30, 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 Liabilities Measured on a Recurring Basis (Details) - Recurring [Member] - Level 2 [Member] $ in Thousands	Sep. 29, 2017USD ($)
Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liabilities	$ (835)
Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liabilities	$ (44)

Restructuring Costs - Summary o

Restructuring Costs - Summary of Restructuring Cost (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 29, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 3,828	$ 13,477
Additions	1,859	11,543
Cash payments	(4,627)	(18,763)
Other adjustments		(2,429)
Ending Balance	1,060	3,828
Severance and Related Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	1,304	4,006
Additions	0	9,357
Cash payments	(1,304)	(12,059)
Other adjustments		0
Ending Balance	0	1,304
Other Restructuring Costs [Member]
Restructuring Reserve [Roll Forward]
Beginning Balance	2,524	9,471
Additions	1,859	2,186
Cash payments	(3,323)	(6,704)
Other adjustments		(2,429)
Ending Balance	$ 1,060	$ 2,524

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 5,611	$ 1,348	$ 16,671	$ 2,370
Effective income tax rate	34.10%	(9.60%)	37.30%	(21.50%)

Separate Financial Informatio46

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Additional Information (Details)	Sep. 29, 2017
Guarantees [Member]
Guarantee Obligations [Line Items]
Percentage of voting stock outstanding in subsidiary guarantors	100.00%

Separate Financial Informatio47

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Unaudited Supplemental Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 29, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 51,978	$ 48,236	$ 60,687	$ 30,022
Receivables, net	341,713	334,248
Assets held for sale, current		20,242
Other current assets	22,754	30,404
Total current assets	416,445	433,130
Property, plant and equipment, net	44,428	46,547
Goodwill	1,078,454	1,078,454
Identifiable intangible assets, net	369,528	393,891
Deferred tax assets	216,234	232,283
Assets held for sale		11,962
Other assets	4,440	2,292
Total assets	2,129,529	2,198,559
Current liabilities:
Current portion of long-term debt	26,947	26,947
Accounts payable, trade	50,413	43,943
Accrued employment costs	96,727	98,860
Accrued expenses	81,965	76,870
Advance payments and billings in excess of costs incurred	31,905	33,259
Deferred income taxes, current and income tax liabilities	518	209
Liabilities held for sale, current		4,341
Other current liabilities	22,396	36,410
Total current liabilities	310,871	320,839
Long-term debt	960,499	1,039,993
Income tax liabilities	63,167	64,852
Liabilities held for sale		1,084
Other liabilities	62,839	66,986
Total liabilities	1,397,376	1,493,754
Shareholders' equity	732,153	704,805
Total liabilities and equity	2,129,529	2,198,559
Engility Holdings, Inc. [Member]
Current assets:
Investment in subsidiaries	732,153	704,805
Total assets	732,153	704,805
Current liabilities:
Shareholders' equity	732,153	704,805
Total liabilities and equity	732,153	704,805
Engility Corporation [Member]
Current assets:
Cash and cash equivalents	36,460	31,124	42,833	18,313
Receivables, net	302,383	280,709
Intercompany receivables	69,131	83,739
Assets held for sale, current		2,332
Other current assets	20,603	27,437
Total current assets	428,577	425,341
Property, plant and equipment, net	38,004	40,071
Goodwill	1,020,027	1,020,027
Identifiable intangible assets, net	337,076	359,465
Deferred tax assets	193,074	213,296
Investment in subsidiaries	74,416	89,543
Other assets	4,395	2,292
Total assets	2,095,569	2,150,035
Current liabilities:
Current portion of long-term debt	26,947	26,947
Accounts payable, trade	50,293	43,848
Intercompany payable	6,284	758
Accrued employment costs	84,809	87,199
Accrued expenses	81,593	76,520
Advance payments and billings in excess of costs incurred	31,905	33,259
Deferred income taxes, current and income tax liabilities	312
Other current liabilities	21,643	34,398
Total current liabilities	303,786	302,929
Long-term debt	960,499	1,039,993
Income tax liabilities	63,167	64,852
Other liabilities	35,964	37,456
Total liabilities	1,363,416	1,445,230
Shareholders' equity	732,153	704,805
Total liabilities and equity	2,095,569	2,150,035
Subsidiary Guarantors [Member]
Current assets:
Cash and cash equivalents	126	385	1,101	29
Receivables, net	22,126	34,655
Assets held for sale, current		17,910
Other current assets	402	506
Total current assets	22,654	53,456
Property, plant and equipment, net	6,346	6,345
Goodwill	58,427	58,427
Identifiable intangible assets, net	32,452	34,426
Deferred tax assets	23,160	18,987
Assets held for sale		11,962
Investment in subsidiaries	30,349	29,248
Other assets	45
Total assets	173,433	212,851
Current liabilities:
Accounts payable, trade	45	37
Intercompany payable	69,131	83,739
Accrued employment costs	2,955	4,530
Liabilities held for sale, current		4,341
Other current liabilities	11	47
Total current liabilities	72,142	92,694
Liabilities held for sale		1,084
Other liabilities	26,875	29,530
Total liabilities	99,017	123,308
Shareholders' equity	74,416	89,543
Total liabilities and equity	173,433	212,851
Subsidiary Non-guarantors [Member]
Current assets:
Cash and cash equivalents	15,392	16,727	$ 16,753	$ 11,680
Receivables, net	17,204	18,884
Intercompany receivables	6,284	758
Other current assets	1,749	2,461
Total current assets	40,629	38,830
Property, plant and equipment, net	78	131
Total assets	40,707	38,961
Current liabilities:
Accounts payable, trade	75	58
Accrued employment costs	8,963	7,131
Accrued expenses	372	350
Deferred income taxes, current and income tax liabilities	206	230
Other current liabilities	742	1,944
Total current liabilities	10,358	9,713
Total liabilities	10,358	9,713
Shareholders' equity	30,349	29,248
Total liabilities and equity	40,707	38,961
Consolidating Adjustments [Member]
Current assets:
Intercompany receivables	(75,415)	(84,497)
Total current assets	(75,415)	(84,497)
Investment in subsidiaries	(836,918)	(823,596)
Total assets	(912,333)	(908,093)
Current liabilities:
Intercompany payable	(75,415)	(84,497)
Deferred income taxes, current and income tax liabilities		(21)
Other current liabilities		21
Total current liabilities	(75,415)	(84,497)
Total liabilities	(75,415)	(84,497)
Shareholders' equity	(836,918)	(823,596)
Total liabilities and equity	$ (912,333)	$ (908,093)

Separate Financial Informatio48

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Unaudited Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Revenue	$ 487,144	$ 511,800	$ 1,467,030	$ 1,570,011
Costs and expenses
Cost of revenue	417,581	435,594	1,255,603	1,341,826
Selling, general and administrative expenses	33,308	39,337	107,303	129,780
Total costs and expenses	450,889	474,931	1,362,906	1,471,606
Operating income	36,255	36,869	104,124	98,405
Interest expense, net	19,739	50,855	59,189	109,358
Other expenses (income), net	49		212	82
Income (loss) before provision for income taxes	16,467	(13,986)	44,723	(11,035)
Provision for income taxes	5,611	1,348	16,671	2,370
Net income (loss)	10,856	(15,334)	28,052	(13,405)
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Net income (loss) attributable to Engility	9,805	(16,757)	24,369	(17,493)
Net income (loss)	10,856	(15,334)	28,052	(13,405)
Other comprehensive income (loss)	(55)	523	(639)	2,331
Comprehensive income (loss)	10,801	(14,811)	27,413	(11,074)
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Comprehensive income (loss) attributable to Engility	9,750	(16,234)	23,730	(15,162)
Engility Holdings, Inc. [Member]
Costs and expenses
Income (loss) in equity investments in subsidiaries	9,805	(16,757)	24,369	(17,493)
Income (loss) before provision for income taxes	9,805	(16,757)	24,369	(17,493)
Net income (loss)	9,805	(16,757)	24,369	(17,493)
Net income (loss) attributable to Engility	9,805	(16,757)	24,369	(17,493)
Net income (loss)	9,805	(16,757)	24,369	(17,493)
Comprehensive income (loss)	9,805	(16,757)	24,369	(17,493)
Comprehensive income (loss) attributable to Engility	9,805	(16,757)	24,369	(17,493)
Engility Corporation [Member]
Revenue	430,261	428,217	1,283,964	1,303,403
Costs and expenses
Cost of revenue	360,520	348,629	1,075,098	1,068,725
Selling, general and administrative expenses	29,240	29,549	94,430	103,581
Total costs and expenses	389,760	378,178	1,169,528	1,172,306
Operating income	40,501	50,039	114,436	131,097
Interest expense, net	19,739	50,855	59,189	109,358
Other expenses (income), net	(7)	(66)	(19)	(99)
Income (loss) in equity investments in subsidiaries	(5,534)	(14,710)	(15,024)	(40,289)
Income (loss) before provision for income taxes	15,235	(15,460)	40,242	(18,451)
Provision for income taxes	5,430	1,297	15,873	(958)
Net income (loss)	9,805	(16,757)	24,369	(17,493)
Net income (loss) attributable to Engility	9,805	(16,757)	24,369	(17,493)
Net income (loss)	9,805	(16,757)	24,369	(17,493)
Other comprehensive income (loss)	(44)	523	(536)	1,699
Comprehensive income (loss)	9,761	(16,234)	23,833	(15,794)
Comprehensive income (loss) attributable to Engility	9,761	(16,234)	23,833	(15,794)
Subsidiary Guarantors [Member]
Revenue	22,199	45,689	75,596	148,117
Costs and expenses
Cost of revenue	25,343	52,537	83,613	165,385
Selling, general and administrative expenses	2,925	8,980	9,766	23,873
Total costs and expenses	28,268	61,517	93,379	189,258
Operating income	(6,069)	(15,828)	(17,783)	(41,141)
Other expenses (income), net	(1)		(3)
Income (loss) in equity investments in subsidiaries	715	1,169	3,554	4,180
Income (loss) before provision for income taxes	(5,353)	(14,659)	(14,226)	(36,961)
Provision for income taxes	181	51	798	3,328
Net income (loss)	(5,534)	(14,710)	(15,024)	(40,289)
Net income (loss) attributable to Engility	(5,534)	(14,710)	(15,024)	(40,289)
Net income (loss)	(5,534)	(14,710)	(15,024)	(40,289)
Other comprehensive income (loss)	(11)		(103)	632
Comprehensive income (loss)	(5,545)	(14,710)	(15,127)	(39,657)
Comprehensive income (loss) attributable to Engility	(5,545)	(14,710)	(15,127)	(39,657)
Subsidiary Non-guarantors [Member]
Revenue	34,684	37,894	107,470	118,491
Costs and expenses
Cost of revenue	31,718	34,428	96,892	107,716
Selling, general and administrative expenses	1,143	808	3,107	2,326
Total costs and expenses	32,861	35,236	99,999	110,042
Operating income	1,823	2,658	7,471	8,449
Other expenses (income), net	57	66	234	181
Income (loss) before provision for income taxes	1,766	2,592	7,237	8,268
Net income (loss)	1,766	2,592	7,237	8,268
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Net income (loss) attributable to Engility	715	1,169	3,554	4,180
Net income (loss)	1,766	2,592	7,237	8,268
Comprehensive income (loss)	1,766	2,592	7,237	8,268
Less: Net income attributable to non-controlling interest	1,051	1,423	3,683	4,088
Comprehensive income (loss) attributable to Engility	715	1,169	3,554	4,180
Consolidating Adjustments [Member]
Costs and expenses
Income (loss) in equity investments in subsidiaries	(4,986)	30,298	(12,899)	53,602
Income (loss) before provision for income taxes	(4,986)	30,298	(12,899)	53,602
Net income (loss)	(4,986)	30,298	(12,899)	53,602
Net income (loss) attributable to Engility	(4,986)	30,298	(12,899)	53,602
Net income (loss)	(4,986)	30,298	(12,899)	53,602
Comprehensive income (loss)	(4,986)	30,298	(12,899)	53,602
Comprehensive income (loss) attributable to Engility	$ (4,986)	$ 30,298	$ (12,899)	$ 53,602

Separate Financial Informatio49

Separate Financial Information of Subsidiary Guarantor of Indebtedness - Unaudited Supplemental Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Operating activities:
Net cash provided by (used in) operating activities	$ 78,755	$ 84,744
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
Capital expenditures	(5,810)	(17,942)
Net cash provided by (used in) investing activities	19,441	(17,942)
Financing activities:
Gross borrowings from issuance of long-term debt		1,180,000
Repayment of long-term debt	(86,410)	(1,199,018)
Gross borrowings from revolving credit facility	270,000	73,000
Repayments of revolving credit facility	(270,000)	(73,000)
Debt issuance costs		(9,988)
Proceeds from share-based payment arrangements		214
Payment of employee withholding taxes on share-based compensation	(1,501)	(1,777)
Dividends paid	(407)	(1,703)
Distributions to non-controlling interest member	(6,136)	(3,865)
Net cash used in financing activities	(94,454)	(36,137)
Net change in cash and cash equivalents	3,742	30,665
Cash and cash equivalents, beginning of period	48,236	30,022
Cash and cash equivalents, end of period	51,978	60,687
Engility Holdings, Inc. [Member]
Financing activities:
Proceeds from share-based payment arrangements		214
Payment of employee withholding taxes on share-based compensation	(1,501)	(1,777)
Dividends paid	(407)	(1,703)
Due (to) from subsidiaries	1,908	3,266
Engility Corporation [Member]
Operating activities:
Net cash provided by (used in) operating activities	54,079	137,046
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
Capital expenditures	(5,810)	(17,942)
Net cash provided by (used in) investing activities	19,441	(17,942)
Financing activities:
Gross borrowings from issuance of long-term debt		1,180,000
Repayment of long-term debt	(86,410)	(1,199,018)
Gross borrowings from revolving credit facility	270,000	73,000
Repayments of revolving credit facility	(270,000)	(73,000)
Debt issuance costs		(9,988)
Due (to) from subsidiaries	18,226	(65,578)
Net cash used in financing activities	(68,184)	(94,584)
Net change in cash and cash equivalents	5,336	24,520
Cash and cash equivalents, beginning of period	31,124	18,313
Cash and cash equivalents, end of period	36,460	42,833
Subsidiary Guarantors [Member]
Operating activities:
Net cash provided by (used in) operating activities	14,349	(64,341)
Financing activities:
Due (to) from subsidiaries	(14,608)	65,413
Net cash used in financing activities	(14,608)	65,413
Net change in cash and cash equivalents	(259)	1,072
Cash and cash equivalents, beginning of period	385	29
Cash and cash equivalents, end of period	126	1,101
Subsidiary Non-guarantors [Member]
Operating activities:
Net cash provided by (used in) operating activities	10,327	12,039
Financing activities:
Distributions to non-controlling interest member	(6,136)	(3,865)
Due (to) from subsidiaries	(5,526)	(3,101)
Net cash used in financing activities	(11,662)	(6,966)
Net change in cash and cash equivalents	(1,335)	5,073
Cash and cash equivalents, beginning of period	16,727	11,680
Cash and cash equivalents, end of period	$ 15,392	$ 16,753