Engility 10-Q 12 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	4-May-15
Document And Entity Information [Abstract]
Entity Registrant Name	Engility Holdings, Inc.
Entity Central Index Key	1544229
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding (in shares)		36,752,262

Unaudited_Consolidated_Balance

Unaudited Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$32,223	$7,123
Receivables, net	434,738	286,403
Prepaid and deferred income taxes, current	33,890	296
Other current assets	31,980	27,488
Total current assets	532,831	321,310
Property, plant and equipment, net	34,009	19,839
Goodwill	1,383,518	644,554
Identifiable intangible assets, net	477,403	123,549
Deferred tax assets	178,092	4,793
Other assets	27,168	8,591
Total assets	2,633,021	1,122,636
Current liabilities:
Current portion of long-term debt	8,447	13,750
Accounts payable, trade	65,154	49,121
Accrued employment costs	99,278	47,824
Accrued expenses	101,231	71,582
Advance payments and billings in excess of costs incurred	42,124	22,300
Deferred income taxes, current and income taxes payable	551	9,810
Other current liabilities	55,703	21,098
Total current liabilities	372,488	235,485
Long-term debt	1,181,576	279,500
Income tax payable	82,580	79,713
Other liabilities	74,465	51,185
Total liabilities	1,711,109	645,883
Commitments and contingencies (see Note 11)
Equity:
Preferred stock, par value $0.01 per share, 25,000 shares authorized, none issued or outstanding as of March 31, 2015 and December 31, 2014	0	0
Common stock, par value $0.01 per share, 175,000 shares authorized, 36,715 and 17,592 shares issued and outstanding as of March 31, 2015 and December 31, 2014, respectively	367	176
Additional paid-in capital	1,228,219	770,764
Accumulated deficit	-308,910	-295,543
Accumulated other comprehensive income	-8,865	-9,018
Non-controlling interest	11,101	10,374
Total equity	921,912	476,753
Total liabilities and equity	$2,633,021	$1,122,636

Unaudited_Consolidated_Balance1

Unaudited Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
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)	36,715,000	17,592,000
Common stock, shares outstanding (shares)	36,715,000	17,592,000

Unaudited_Consolidated_Stateme

Unaudited Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$402,647	$338,824
Costs and expenses
Cost of revenue	343,465	292,389
Selling, general and administrative expenses	58,879	26,750
Total costs and expenses	402,344	319,139
Operating income	303	19,685
Interest expense, net	18,594	3,057
Other expenses, net	-27
Income (loss) before income taxes	-18,318	16,628
Provision (benefit) for income taxes	-5,677	6,811
Net income (loss)	-12,641	9,817
Less: Net income attributable to non-controlling interest	726	946
Net income (loss) attributable to Engility	($13,367)	$8,871
Earnings (loss) per share attributable to Engility
Basic (USD per share)	($0.55)	$0.52
Diluted (USD per share)	($0.55)	$0.50
Weighted average number of shares outstanding
Basic (shares)	24,379	16,993
Diluted (shares)	24,379	17,894

Unaudited_Consolidated_Stateme1

Unaudited Consolidated Statement of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	($12,641)	$9,817
Pension liability adjustment, net of tax benefit of $97, $0, respectively	153	0
Comprehensive income (loss)	-12,794	9,817
Less: Net income attributable to non-controlling interest	726	946
Comprehensive income (loss) attributable to Engility	($13,520)	$8,871

Unaudited_Consolidated_Stateme2

Unaudited Consolidated Statement of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax	$97	$0

Unaudited_Consolidated_Stateme3

Unaudited Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net income (loss)	($12,641)	$9,817
Share-based compensation	5,293	2,727
Depreciation and amortization	8,457	4,643
Amortization of bank debt fees	5,724	405
Deferred income taxes	9,049	2,195
Changes in operating assets and liabilities, excluding acquired amounts:
Receivables	-363	1,224
Other assets	144	-2,416
Accounts payable, trade	-18,370	1,928
Accrued employment costs	-40,942	-2,048
Accrued expenses	-2,871	-4,656
Advance payments and billings in excess of costs incurred	1,820	2,104
Other liabilities	-3,009	-4,241
Net cash (used in) provided by operating activities	-47,709	11,682
Investing activities:
Acquisition, net of cash acquired	25,478	-207,250
Capital expenditures	-246	-286
Net cash provided by (used in) investing activities	25,232	-207,536
Financing activities:
Gross borrowings from issuance of long-term debt	585,000	75,000
Repayment of long-term debt	-337,337	-3,438
Gross borrowings from revolving credit facility	107,000	190,500
Repayments of revolving credit facility	-60,000	-79,500
Debt issuance costs	-42,425	-1,106
Equity issuance costs	-1,725	0
Proceeds from share-based payment arrangements	279	93
Payment of employee withholding taxes on share-based compensation	-5,953	-2,353
Excess tax deduction on share-based compensation	4,138	1,368
Dividends paid	-201,400	0
Distributions to non-controlling interest member		-2,495
Net cash provided by financing activities	47,577	178,069
Net change in cash and cash equivalents	25,100	-17,785
Cash and cash equivalents, beginning of period	7,123	29,003
Cash and cash equivalents, end of period	$32,223	$11,218

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation
	Description of Business: Engility Holdings, Inc. (Engility) through its predecessors, has provided mission critical services to the U.S. government for over six decades. Engility serves among other federal agencies, the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Agency for International Development (USAID), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and allied foreign governments. With Engility's recent acquisition of TASC, Inc. (TASC) on February 26, 2015, Engility further diversified its portfolio to add leading positions with U.S. national security and public safety agencies, including the National Geospatial-Intelligence Agency (NGA), National Security Agency (NSA), Defense Intelligence Agency (DIA), and other intelligence community agencies. Engility also added space-related agencies such as the National Reconnaissance Organization (NRO), National Aeronautical and Space Administration (NASA), and U.S. Air Force. The acquisition of TASC also enhanced Engility's market position with DHS, Defense Threat Reduction Agency (DTRA), FAA, and Missile Defense Agency (MDA).
	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. On January 31, 2014, we completed the acquisition of Dynamics Research Corporation (DRC) which is more fully described in Note 3 to the accompanying Unaudited Consolidated Financial Statements. On February 26, 2015, we completed the acquisition of TASC which is more fully described in Note 3 to the accompanying Unaudited Consolidated Financial Statements. These transactions were recorded using the purchase method of accounting; accordingly, DRC's and TASC's financial results are included in the Unaudited Consolidated Financial Statements for the periods subsequent to the acquisition.
	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 for the year ended December 31, 2014 (2014 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.
	Change in Accounting Principle for Revenue Recognition: As of January 1, 2015, we changed our methodology of recognizing revenue for all of our U.S. government contracts to apply the accounting guidance of Financial Accounting Standards Board (FASB), Accounting Standard Codification (ASC), or ASC, Subtopic 605-35, as directed by ASC Topic 912, which permits revenue recognition on a percentage-of-completion basis. Previously, we applied this guidance only to contracts related to the construction or development of tangible assets. For contracts not related to those activities, we had applied the general revenue recognition guidance of Staff Accounting Bulletin (SAB), Topic 13, “Revenue Recognition.” We believe that the application of contract accounting under ASC 605-35 to all U.S. government contracts is preferable to the application of contract accounting under SAB Topic 13, based on the fact that the percentage of completion model utilized under ASC 605-35 is a recognized accounting model that better reflects the economics of a U.S. government contract during the contract performance period and better aligns Engility’s revenue policy with its peers.
	The financial impact resulting from the accounting change was immaterial to our financial statements.
	Revenue Recognition: Substantially all of the Company’s revenue is derived from services provided to the U.S. government and its agencies, primarily by the Company’s consulting staff and, to a lesser extent, subcontractors. The Company generates its revenue from the following types of contractual arrangements: cost-reimbursable-plus-fee contracts, time-and-materials contracts, and fixed-price contracts.
	Revenue on cost-reimbursable-plus-fee contracts is recognized as services are performed, generally based on the allowable costs incurred during the period 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, the Company recognizes income when such fees are probable and estimable. 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 percentage-of-completion 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. Profits on fixed-price contracts result from the difference between incurred costs and revenue earned.
	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 the Company’s contracts, developing total revenue and cost at completion estimates requires 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 “out of pocket” costs that often include, but are not limited to, travel-related costs and telecommunications charges. The Company recognizes 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.
	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.
	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.
	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 relate to the recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income tax contingencies and revenue and expenses for certain revenue arrangements. Actual amounts may differ from these estimates and could differ materially.
	Reporting Periods: Our fiscal year begins on January 1 and ends on December 31. Our fiscal quarters end on March 31, June 30, September 30, and December 31.
	Earnings per Share: Basic earnings per share (EPS) is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted EPS reflects potential dilution that could occur if securities to issue common stock were exercised or converted into common stock. Diluted EPS includes the effect of the employee stock purchase plan, restricted stock units (RSU), stock options, performance shares and performance units calculated using the treasury stock method. For the three months ended March 31, 2015 and March 31, 2014, 671,602 shares and no shares were excluded from diluted EPS, respectively.
		Three Months Ended
		March 31, 2015			March 31, 2014
	Net income (loss) attributable to Engility	$	(13,367	)	$	8,871
	Weighted average number of shares outstanding – Basic	24,379			16,993
	Dilutive effect of share-based compensation outstanding after application of the treasury stock method	—			901
	Weighted average number of shares – Diluted	24,379			17,894
	Earnings (loss) per share attributable to Engility
	Basic	$	(0.55	)	$	0.52
	Diluted	$	(0.55	)	$	0.5

New_Accounting_Pronouncements

New Accounting Pronouncements	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements
	In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 outlines a single comprehensive model for entities to use when accounting for revenue arising from contracts with customers and supersedes all current revenue recognition guidance, including industry-specific guidance. This new guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016; early adoption is not permitted. Entities have the option of using either a full retrospective or a modified approach to adopt the guidance. This update could impact the timing and amounts of revenue recognized. On April 1, 2015, the FASB proposed deferring the effective date by one year to December 15, 2017 for annual periods beginning after that date.
	We are currently evaluating the effect that implementation of this update will have on our consolidated financial position and results of operations upon adoption.
	In June 2014, the FASB issued ASU No. 2014-12, Compensation - Stock Compensation (Topic 718) - Accounting for Share-based Payments when Terms of an award Provide That a Performance Target Could be Achieved after the Requisite Service Period. The Amendments in ASU 2014-12 require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. We do not expect this pronouncement to have a material impact on our financial statements.
	In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern.  The guidance requires an entity to evaluate whether there are conditions or events, in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the financial statements are available to be issued when applicable) and to provide related footnote disclosures in certain circumstances.  The guidance is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter.  Early application is permitted.  We do not believe the adoption of this guidance will have a significant impact on our consolidated financial statements.
	In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest, which changes the presentation of debt issuance costs in financial statements. The amendments in this standard require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this standard. The guidance is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter.  We do not believe the adoption of this guidance will have a significant impact on our consolidated financial statements.

Business_Acquisition

Business Acquisition	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Business Acquisition	Business Acquisitions
	TASC Acquisition
	On February 26, 2015, we completed the acquisition of TASC, a leading professional services provider to the national security and public safety markets, in an all-stock transaction. We acquired TASC to further diversify our portfolio to add leading positions with U.S. national security and public safety agency customers, including, the NGA, NSA, DIA, and other intelligence community agencies. We also added space-related agency customers such as the NRO, NASA, and U.S. Air Force. The acquisition of TASC also enhanced our market position with DHS, DTRA, FAA, and MDA. TASC had approximately 4,000 employees located throughout the United States as of February 26, 2015.
	The business combination 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. Accordingly, the combined companies now operate under New East Holdings, Inc. which was renamed “Engility Holdings, Inc.” upon the closing of the acquisition. The New Engility common stock, similar to the predecessor Engility common stock, trades on the New York Stock Exchange (NYSE) under the symbol “EGL.”
	As a result of the acquisition of TASC, former TASC stockholders held approximately 52% of our shares of common stock outstanding as of February 26, 2015, the closing date of the acquisition.
	As a condition to the merger, we entered into a Stockholders Agreement, dated February 26, 2015, with Birch Partners, LP (Birch), and for the limited purposes set forth therein, certain investment funds affiliated with Kohlberg Kravis Roberts & Co. L.P. (KKR) and certain investment funds affiliated with General Atlantic LLC (GA) (the Stockholders Agreement). The Stockholders Agreement establishes certain rights, restrictions and obligations of Birch, KKR and GA, and sets forth certain governance and other arrangements relating to Engility, including the right of Birch to designate (i) four directors for nomination to our board of directors for so long as each of KKR and GA (including their respective affiliates) beneficially own at least 50% of the shares of our common stock it owned as of the date of the Stockholders Agreement and (ii) two directors for nomination to our board of directors for so long as each of KKR and GA (including their respective affiliates) beneficially own at least 25% of the shares of our common stock it owned as of the date of the Stockholders Agreement.
	In connection with the acquisition, we issued 18,937,765 shares of Engility common stock on February 26, 2015 valued at approximately $663 million, and we assumed debt with an estimated fair value of $623 million. Engility declared a special cash dividend payable to shareholders of record as of immediately prior to the closing of the TASC transaction (the Cash Dividend), including holders of all outstanding RSUs and Performance Shares upon vesting, in the amount of $207 million, or $11.434 per share. For holders of unvested RSUs and Performance Shares, the Cash Dividend accrued on such grants and will be delivered to the holders upon the vesting of such grants. For the quarter ended March 31, 2015, Engility paid $201 million pursuant to the Cash Dividend to shareholders and holders of vested RSUs and options. The remaining Cash Dividend balance of $5 million will be paid to holders upon the vesting of their outstanding RSUs and Performance Shares.
	We accounted for the acquisition of TASC Parent Corporation as a business combination under ASC 805 with Engility as the accounting acquirer. We determined Engility was the accounting acquirer in accordance with ASC 805-10-25-5 as Engility gained control of TASC upon completion of the merger. To make this determination we considered factors as indicated in ASC 805-10-55, including which entity issued equity interests to effect the combination, board of director composition, shareholder ownership, voting control, restrictions on shareholder voting rights, anticipated management positions and the relative size of the two companies. Engility issued its equity to effect the combination, which is usually done by the acquirer. The post-acquisition board of directors is comprised of eleven individuals, seven of whom are the Engility directors and the remaining four of whom are designated by Birch Partners, LP (Birch), the holder of approximately 99% of the outstanding common stock of TASC prior to the acquisition. While the shareholders of TASC own approximately 52% of the combined company common stock following the closing of the transaction, Birch executed, at the closing of the transaction, a stockholders agreement agreeing to vote (i) until it no longer has any director nomination rights, with respect to the election of directors, all of its shares in the same manner as, and in the same proportion to, all shares as voted by Engility stockholders (excluding the votes of Birch), other than with respect to its four director nominees; and (ii) with respect to all other proposals, all of its shares in excess of 30% of the total voting power of all issued and outstanding shares of the combined company (between 21% and 21.5% initially) in the same manner as, and in the same proportion to, all shares as voted by Engility stockholders (excluding the votes of Birch). Thus, with respect to proposals other than the election of directors, Birch only controls and is able to independently vote an aggregate of 30% of the outstanding shares of the combined company. Birch is not be able to transfer ownership for years one through three following the closing of the transaction and is limited in years four through six. The combined Engility company is led by Engility’s current President and Chief Executive Officer, Anthony Smeraglinolo, and John Hynes, TASC’s former President and Chief Executive Officer, became the Chief Operating Officer of the combined company, reporting to Mr. Smeraglinolo. Another consideration was the relative size of the two companies. Engility had greater revenue, total assets, earnings before interest, taxes, depreciation, and amortization (EBITDA), pre-tax income and employees. All of the above mentioned factors have led us to conclude that Engility was the accounting acquirer.
	We are in the process of finalizing the valuation of the TASC-related assets acquired and liabilities assumed, in particular those requiring significant judgment including evaluating lease values, liabilities, and reserves. The preliminary allocation of purchase price is as follows:
	Number of Engility shares issued				18,937,765
	Share price on February 26, 2015	$	46.45
	Dividend payable to Engility shareholders	11.434
	Value of Engility shares issued to TASC shareholders				$	35.016
	Equity consideration							$	663,125
	Cash							$	25,478
	Receivables							147,972
	Prepaid and deferred income taxes, current							22,106
	Other current assets							26,026
	Property, plant and equipment							15,835
	Deferred tax assets							177,889
	Other assets							5,096
	Current portion of long-term debt							(4,097		)
	Accounts payable, trade							(34,403		)
	Accrued employment costs							(92,396		)
	Accrued expenses							(32,520		)
	Advance payments and billings in excess of costs incurred							(18,004		)
	Deferred income taxes, current and income taxes payable							(247		)
	Other current liabilities							(31,301		)
	Long-term debt							(619,227		)
	Other long-term liabilities							(24,446		)
	Identifiable intangible assets							360,400
	Goodwill							738,964
								$	663,125
	The goodwill arising from the TASC acquisition consists largely of the specialized nature of the workforce as well as the synergies and economies of scale expected from combining the operations of Engility and TASC and their respective subsidiaries. The goodwill arising from the TASC acquisition is not tax deductible.
	The valuation of the identified intangible assets acquired is summarized below:
		Useful Life (years)
	Customer contractual relationships	15		$	335,700
	Contractual backlog	1		17,700
	Technology	15		7,000
	Total intangible assets			$	360,400
	From the date of acquisition, February 26, 2015, through March 31, 2015, TASC generated $99 million of revenue and operating net loss of $6 million. During the three months ended March 31, 2015, we incurred $28 million of acquisition-related costs which are reflected in selling, general and administrative expenses.
	The following pro forma results of operations have been prepared as though the acquisition of TASC had occurred on January 1, 2014. These pro forma results include adjustments for (1) amortization expense for the estimated identifiable intangible assets in the preliminary allocation of purchase price, (2) the removal of historical TASC amortization expense, (3) adjustments to conform TASC policies to Engility's policies related to the timing and recognition of certain contract revenue and costs, (4) the alignment of TASC’s financial calendar to that of Engility’s and 5) the removal of acquisition-related expenses incurred and recorded in each of TASC and Engility’s results of operations in the three months ended March 31, 2015, and a related adjustment to record such costs in the three months ended March 31, 2014.
	The pro forma results of operations also include adjustments to reflect the acquisition of DRC, which was acquired January 31, 2014, as though the acquisition occurred on January 1, 2013. These pro forma results include adjustments for (1) amortization expense for the identifiable intangible assets in the final purchase price allocation, (2) the removal of historical DRC amortization expense, and (3) the removal of acquisition-related expenses incurred and recorded on each of DRC and Engility’s results of operations in the three months ended March 31, 2014.
	This pro forma information does not purport to be indicative of the results of operations that would have been attained had the acquisitions been made as of January 1, 2014 and January 1, 2013 respectively, or of results of operations that may occur in the future.
		Three Months Ended
		March 31, 2015				March 31, 2014
	Revenue	$	561,935			$	637,300
	Operating income (loss)	26,801				(8,156		)
	DRC Acquisition
	On January 31, 2014, we completed the acquisition of DRC pursuant to a definitive agreement dated December 20, 2013. We paid $11.50 per share for DRC, for an aggregate purchase price of approximately $207 million in cash (including the retirement of approximately $86 million of indebtedness of DRC). As a result of the acquisition, DRC is now an indirect wholly-owned subsidiary of Engility.
	DRC is a leading provider of innovative management consulting, engineering, technical, information technology services and solutions to federal and state governments. We acquired DRC to create a stronger, more efficient organization to support our customers with a wider range of specialized technology and mission expertise. This acquisition is consistent with our strategy to expand our addressable market, customer base and capabilities. In addition, it increased our access to key contract vehicles, added scale to our business and further diversified our revenue base.
	The final allocation of purchase price is as follows:
	Cash consideration	$	207,250
	Receivables	$	43,246
	Other current assets	2,135
	Property, plant and equipment	8,604
	Other assets	5,985
	Accounts payable, trade	(15,436		)
	Accrued employment costs	(16,845		)
	Accrued expenses	(4,735		)
	Advance payments and billings in excess of costs incurred	(309		)
	Deferred income taxes, current and income taxes payable	1,208
	Other current liabilities	(4,041		)
	Income tax payable	(800		)
Other long-term liabilities	(24,912		)
Identifiable intangible assets	46,200
Goodwill	166,950
	$	207,250
The goodwill arising from the DRC acquisition consists largely of the specialized nature of the workforce as well as the synergies and economies of scale expected from combining the operations of Engility and DRC and their respective subsidiaries. The goodwill arising from the DRC acquisition is not tax deductible.
The valuation of the identified intangible assets acquired is summarized below:
	Useful Life (years)
Customer contractual relationships	16		$	42,100
Contractual backlog	1		4,100
Total intangible assets			$	46,200
From the date of acquisition, January 31, 2014, through March 31, 2014, DRC generated $39 million of revenue and operating net loss of $1 million.

Receivables

Receivables	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Receivables	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.
		As of			As of
		March 31,			December 31,
		2015			2014
	Billed receivables	$	147,235		$	115,500
	Unbilled receivables	289,174			172,385
	Allowance for doubtful accounts	(1,671		)	(1,482		)
	Total receivables, net	$	434,738		$	286,403

Goodwill_and_Identifiable_Inta

Goodwill and Identifiable Intangible Assets	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Identifiable Intangible Assets	Goodwill and Identifiable Intangible Assets
	Goodwill: In accordance with the accounting standards for business combinations, we record the assets acquired and liabilities assumed based on their estimated fair values at the date of the acquisition (commonly referred to as the purchase price allocation). Goodwill was $1,384 million and $645 million at March 31, 2015 and December 31, 2014, respectively. Goodwill increased by $739 million during the three months ended March 31, 2015 as a result of the TASC acquisition.
	Identifiable Intangible Assets: Information on our identifiable intangible assets that are subject to amortization is presented in the table below.
				March 31, 2015								31-Dec-14
		Weighted Average Remaining Useful Life		Gross				Accumulated		Net		Gross		Accumulated		Net
				Carrying				Amortization		Carrying		Carrying		Amortization		Carrying
				Amount						Amount		Amount				Amount
		(in years)
	Customer contractual relationships	17		$	556,430			$	102,216	$	454,214	$	220,730	$	97,523	$	123,207
	Contractual Backlog	1		21,800				5,575		16,225		4,100		3,758		342
	Technology	15		7,000				36		6,964		—		—		—
	Total			$	585,230			$	107,827	$	477,403	$	224,830	$	101,281	$	123,549
	Our amortization expense recorded for our identifiable intangible assets is presented in the table below.
		Three Months Ended
		March 31, 2015				March 31, 2014
	Amortization expense	$	6,546			$	3,303

ShareBased_Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation
	For the three months ended March 31, 2015
	Effect of TASC Transaction on Engility Equity Awards
	The TASC transaction constituted a change of control under the grant agreements for Engility's outstanding restricted stock units (RSUs), stock options, and performance shares. The impact on these equity grants was as follows:
	RSUs: Pursuant to the terms of the RSU grant agreements, 364,983 RSUs held by our employees vested. Certain executive officers waived vesting with respect to 229,166 RSUs and our non-executive directors waived vesting with respect to 11,790 RSUs. The TASC transaction also triggered the issuance of shares for 43,950 vested RSUs held by the non-executive members of our Board of Directors, pursuant to the terms of the grant agreements for these RSUs.
	Stock Options: Pursuant to the terms of the stock option grant agreements, the exercise price adjusted to reflect the Cash Dividend, provided, that to the extent that adjusting the exercise price by the full amount of the Cash Dividend resulted in the exercise price of the stock options falling below 25% of the fair market value of the shares underlying such stock options, such excess portion of the Cash Dividend was paid to holders of the affected stock options in cash.
	Performance Shares: Pursuant to the terms of the performance share agreements, we fixed the number of underlying shares that are eligible to be vested and issued with respect to our outstanding grants of performance shares. For the performance shares granted in 2013, the number of eligible underlying shares was fixed at 127% of their target value based on Engility's performance against the financial metrics set forth in the grant agreements, measured as of a shortened performance period prior to the closing date of the TASC transaction in accordance with the terms of the award agreements. For the 2014 grants of performance shares, as less than half of the performance period was complete at the time of the closing of the TASC transaction, the number of underlying shares was fixed at their target value of 100% in accordance with the terms of the award agreements.
	The performance shares cliff vest according to their grant agreement dates, three years from grant date.
	New Awards Granted
	Performance Retention Awards: During the three months ended March 31, 2015, we granted 212,963 performance units at a target level of 100% (with the potential for the delivery of up to 425,926 shares at the maximum performance level) to certain of our executives with a grant date fair value of $32.82. The performance retention awards cliff vest after three years based on our performance at the end of a three-year period beginning January 1, 2015. The number of shares of our common stock that are ultimately vested and delivered in respect of these performance retention awards will range from 50% to 200% of the target grant amount depending on the Company’s performance against a metric of net debt to adjusted EBITDA, measured as of December 31, 2017. The performance retention awards may be settled in cash or stock at the sole discretion of the Compensation Committee.
	Performance Units: During the three months ended March 31, 2015, we granted 191,848 performance units at target level of 100% (with the potential for the delivery of up to 431,658 shares at the maximum performance level) to certain of our employees with a grant date fair value of $32.29. Performance units cliff vest after three years based on our performance at the end of a three-year period beginning January 1, 2015. 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 depending 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. At the end of the three-year period beginning on January 1, 2015, the vested performance units will be subject to further adjustment based on our total stockholder return (TSR) measured against the TSR of a peer group of companies previously approved by the Compensation Committee. If Engility is in the bottom quartile of TSR relative to its peer group, the ultimate number of shares of stock delivered with respect to the performance units will be reduced by 25% of their target number. If Engility is in the top quartile of TSR relative to its peer group, the ultimate number of shares of stock delivered with respect to the performance units will be increased by 25% of their target number. If Engility’s TSR falls within the middle two quartiles relative to its peer group, there will be no adjustment to the number of shares delivered. The performance units may be settled in cash or stock at the sole discretion of the Compensation Committee.
	Restricted Stock Units: During the three months ended March 31, 2015, we granted 127,899 RSUs to certain of our employees with a grant date fair value of $32.82, which 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. During the three months ended March 31, 2015, we granted 2,482 RSUs to certain of the non-management members of our Board of Directors with a grant date fair value of $32.82, which vest on May 21, 2015, the date of our annual meeting.
	The employee and director RSUs may be settled in cash or stock upon vesting at the sole discretion of the Compensation Committee.
	For the three months ended March 31, 2014
	Performance Shares: During the three months ended March 31, 2014, we granted 102,961 performance shares at a target level of 100% (205,922 shares at the maximum performance level) to certain of our employees with a weighted average grant date fair value of $56.14. Performance shares cliff vest after three years based on our performance at the end of a three-year period beginning January 1, 2014. The number of shares of our common stock that are ultimately vested and retained in respect of these performance shares will range from 0% to 200% of the target grant amount depending on the Company’s performance against a peer group, as approved by the Compensation Committee of our Board of Directors, based on the following two metrics, each of which are weighted equally: relative revenue (based on a compounded annual growth rate) and relative TSR. No shares will vest, including with respect to relative revenue, if we do not achieve at least a threshold level of performance for TSR.
	As discussed above, in conjunction with the TASC acquisition, the number of shares eligible to vest pursuant to the performance share awards became fixed.
	Restricted Stock Units: During the three months ended March 31, 2014, we granted 72,869 RSUs to certain of our employees with a weighted average grant date fair value of $44.33. 68,633 of these 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. The remaining 4,236 of these RSUs, which were only provided to non-executive employees, cliff vest on the first anniversary of the grant date. These RSUs automatically convert into shares of Engility common stock upon vesting, and are subject to forfeiture until certain restrictions have lapsed. As discussed above, the vesting of all of these RSUs was accelerated and the underlying shares were delivered to the holders as a result of the TASC acquisition, with the exception of RSUs held by certain of our executive officers, for which acceleration was waived.

Defined_Benefit_Pension_Plan

Defined Benefit Pension Plan	3 Months Ended
	Mar. 31, 2015
Postemployment Benefits [Abstract]
Defined Benefit Pension Plan	Defined Benefit Pension Plan
	DRC Pension
	Upon the acquisition of DRC, we assumed DRC's Defined Benefit Pension Plan (the Pension Plan), which is non-contributory, covering substantially all employees of DRC who had completed a year of service prior to July 1, 2002. Membership in the Pension Plan was frozen effective July 1, 2002 and participants’ calculated pension benefit was frozen effective December 31, 2006.
	Our funding policy is to contribute at least the minimum amount required by the Employee Retirement Income Security Act of 1974. Additional amounts are contributed to assure that plan assets will be adequate to provide retirement benefits. We expect to make no contributions during the remainder of 2015 to fund the pension plan.
	The components of net periodic pension income for the Pension Plan for the three months ended March 31, 2015 and 2014 are as follows:
		Three Months Ended
		March 31, 2015			31-Mar-14
	Interest cost on projected benefit obligation	$	991		$	652
	Expected return on plan assets	(1,466		)	(970		)
	Net loss amortization	49			—
	Net periodic pension expense (income)	$	(426	)	$	(318	)
	TASC Defined Benefit Plan
	Upon the closing of the TASC acquisition, we assumed TASC's defined benefit plan in which certain employees are eligible to participate based upon service with the TASC's prior parent. This plan offers two retirement programs, a Retiree Health Reimbursement Account Plan (RHRA) and a Cash Bonus Plan, which provide a restoration of certain pension benefits that would have been forfeited as a result of years of service and final average pay being frozen by TASC's prior parent. The liability of the TASC defined benefit plan was $21 million on the date of acquisition.

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt	Debt
	2015 Credit Facility
	In connection with the acquisition of TASC, which included the payment of the Cash Dividend and the repayment of outstanding debt under our 2013 Credit Facility (as defined below), we borrowed $585 million under a promissory note issued by our wholly-owned subsidiary Engility LLC (f/k/a Engility Corporation) and guaranteed by Predecessor Engility (as defined below) and certain other Predecessor Engility (as defined below) subsidiaries (the Engility Bridge Loan). In addition, we guaranteed the debt of TASC comprised of the First Lien Credit Agreement and the Second Lien Credit Agreement, consisting of (a)(i) a $395 million senior secured first lien term loan facility (the Original First Lien Term Facility), (ii) a $50 million senior secured revolving credit facility and (iii) a $250 million senior secured second lien term loan facility (the Original Second Lien Term Facility) (the existing facilities in clauses (a)(i) through (a)(iii), collectively, the TASC Existing Credit Facilities) and (b)(i) a new $435 million senior secured first lien term loan facility (the Incremental First Lien Term Facility), (ii) additional senior secured first lien revolving credit capacity in an aggregate principal amount of $65 million and (iii) a new $150 million senior secured second lien term loan facility (the Incremental Second Lien Term Facility) (the incremental facilities in clauses (b)(i) through (iii), collectively, the TASC Incremental Facilities and along with the TASC Existing Credit Facilities, the 2015 Credit Facility), in each case with Barclays Bank PLC as administrative agent. As of March 31, 2015, after repayment in full of the 2013 Credit Facility (as defined below) with proceeds of the Engility Bridge Loan, which was then followed by repayment in full of the with proceeds of the TASC Incremental Facilities, each on February 26, 2015, our total outstanding principal balance under the 2015 Credit Facility was $1,231 million.
	Maturity, Interest Rate and Fees. All borrowings under the 2015 Credit Facility pursuant to the First Lien Credit Agreement bear interest at a variable rate per annum equal to an applicable margin, plus, at our option (other than for swing line loans), either (1) a base rate determined by reference to the highest of (a) the prime rate of Barclays Bank PLC, (b) the federal funds effective rate plus 0.50% and (c) a LIBOR rate determined by reference to the cost of funds for U.S. dollar deposits for the interest period of one month, plus 1.00% or (2) a LIBOR rate determined by reference to the costs of funds for U.S. dollar deposits for the interest period relevant to such borrowing, provided that for the Original First Lien Term Facility and Incremental First Lien Term Facility, the LIBOR rate shall not be less than 1.0%. All swing line loans bear interest at a variable rate per annum equal to an applicable margin, plus a base rate determined as described in the immediately preceding sentence. The applicable LIBOR margin and the applicable base rate margin for borrowings under the First Lien Credit Agreement are 6.00% and 5.00%, respectively. All borrowings under the TASC Credit Facility pursuant to the Second Lien Credit Agreement bear interest at a rate per annum equal to 12.00%.
	Guarantee and Security. All obligations under the 2015 Credit Facility are unconditionally guaranteed by TASC Parent Corporation, which was converted to a limited liability company immediately following the consummation of the acquisition of TASC (“TASC Parent LLC”), and certain of TASC Parent LLC’s existing direct or indirect wholly owned domestic subsidiaries, and will be required to be guaranteed by certain of TASC Parent LLC’s future direct or indirect wholly owned domestic subsidiaries. All obligations under the 2015 Credit Facility, and guarantees of those obligations, are secured, subject to certain exceptions, by substantially all of the assets of TASC Parent LLC and its subsidiary guarantors. In connection with the closing of the acquisition of TASC, Engility LLC and certain of its subsidiaries now guarantee and provide security for all indebtedness of TASC described above, including the 2015 Credit Facility and any financing replacing or refinancing the 2015 Credit Facility.
	The terms of the 2015 Credit Facility permit prepayment and termination of the loan commitments at any time, subject to certain conditions, including, but not limited to, the payment of certain prepayment and make-whole premiums. The 2015 Credit Facility also contains various covenants, including certain financial covenants, affirmative covenants with respect to certain reporting requirements and maintaining certain business activities, and negative covenants that, among other things, may limit or impose restrictions on the ability of the Company and its subsidiaries to incur liens, incur additional indebtedness, make investments, make acquisitions and undertake certain other actions. In addition, TASC Parent LLC is also subject to a passive holding company covenant that limits its ability to engage in certain activities. The 2015 Credit Facility also contains certain customary provisions related to events of default (including upon a change of control).
	Amortization and Final Maturity. We are required to make scheduled quarterly payments equal to 0.25% of the original principal amount of the Original First Lien Term Facility and the Incremental First Lien Term Facility under the 2015 Credit Facility, with the balance due and payable on May 23, 2020. The Original Second Lien Term Facility and Incremental Second Lien Term Facility are due on May 23, 2021.
	Covenants and Events of Default. The 2015 Credit Facility contains a number of covenants that, among other things and subject to certain exceptions, restrict our ability to incur additional debt; pay dividends on our capital stock or redeem, repurchase or retire our capital stock or other debt; make investments, loans and acquisitions; create restrictions on the payment of dividends or other amounts by TASC Parent LLC subsidiaries to TASC Parent LLC or to any guarantor; engage in transactions with TASC Parent LLC’s affiliates; sell assets; consolidate, merge, dissolve or wind up our business; incur liens; and prepay or amend subordinated or unsecured debt. In addition, the 2015 Credit Facility requires that TASC Parent LLC maintain a maximum consolidated total net leverage ratio of no greater than 6.75:1.00 as of the end of any fiscal quarter of TASC Parent LLC, with step-downs to 6.50:1.00 beginning with the fiscal quarter ended December 31, 2015, 6.00:1.00 beginning with the fiscal quarter ending June 30, 2016, 5.50:1.00 beginning with the fiscal quarter ending December 31, 2016, 5.00:1.00 beginning with the fiscal quarter ending December 31, 2017, and 4.50:1.00 beginning with the fiscal quarter ending December 31, 2018. We believe our most restrictive covenant under the 2015 Credit Facility is the maximum consolidated leverage ratio, which as of March 31, 2015 was 4.76:1.00. The consolidated total net leverage ratio is the ratio of (a) (i) funded debt as of such date minus (ii) the unrestricted cash as of such date to (b) consolidated EBITDA for the period of the four fiscal quarters most recently ended. The 2015 Credit Facility also contains customary provisions relating to the events of default.
	In connection with the February 26, 2015 TASC Incremental Facilities, the Company expensed $5 million of deferred debt issuance costs associated with the 2013 Credit Facility. Furthermore, the Company expensed debt issuance costs of approximately $1 million that did not qualify for deferral. These amounts are reflected in interest expense, net in the Unaudited Consolidated Statements of Operations.
	Our weighted average outstanding loan balance for the three months ended March 31, 2015 was $662 million under the 2015 Credit Facility which accrued interest at a weighted average borrowing rate of approximately 7.43%. As of March 31, 2015, we were in compliance with the covenants under the 2015 Credit Facility.
	The carrying value of the term loan excluding original issue discount, which approximates fair value, is $1,206 million. The fair value of the term loan is 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. Our availability under the revolving portion of the 2015 Credit Facility was $106 million as of March 31, 2015, with $4 million outstanding under letters of credit.
	2013 Credit Facility
	On August 9, 2013, Engility Holdings, Inc., as the predecessor to New Engility (Predecessor Engility), through its wholly-owned subsidiary Engility LLC (f/k/a Engility Corporation), entered into a credit facility among Predecessor Engility, Engility LLC, Bank of America, N.A. (as administrative agent, swing line lender and letter of credit issuer) and each of the several lenders from time to time party thereto, which credit facility was amended on January 31, 2014 (as amended, 2013 Credit Facility). The 2013 Credit Facility, which replaced a prior credit facility, provided for (1) a $275 million term loan facility maturing on August 9, 2018 and (2) a $325 million revolving credit facility terminating on August 9, 2018, with a $50 million letter of credit sublimit and a $25 million swing line loan sublimit. The 2013 Credit Facility also contained an accordion feature that permitted Engility LLC to arrange with the lenders for the provision of up to $150 million in additional commitments.
	During the three months ended March 31, 2014, we had a weighted average outstanding loan balance of $320 million under the 2013 Credit Facility, which accrued interest at a weighted average borrowing rate of approximately 2.95%. On February 26, 2015, the 2013 Credit Facility was repaid in connection with our entry into the TASC Incremental Facilities described above.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	The Company utilizes fair value measurement guidance prescribed by U.S. GAAP to value its financial instruments. The guidance includes a definition of fair value, prescribes methods for measuring fair value, establishes a fair value hierarchy based on the inputs used to measure fair value and expands disclosures about the use of fair value measurements. Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.
	Derivatives: The Company has entered into multiple interest rate swap contracts which reduce the 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 shareholders’ equity (as a component of accumulated other comprehensive income (loss)) and would be subsequently reclassified into earnings in the same period or periods during which the hedged forecasted transaction affects earnings. The ineffective portion of the gain or loss of a cash flow hedge would be reported in earnings. The Company does not have any derivatives outstanding that are not designated as hedges.
	The Company’s liabilities are measured at fair value on a recurring basis as of March 31, 2015 and February 26, 2015, the TASC acquisition date, and are aggregated by the level in the fair value hierarchy within which those measurements fall. All instruments are classified as Level 2 and there were no transfers of financial instruments between the three levels of fair value hierarchy during the period ended March 31, 2015 and February 26, 2015. The following table presents our liabilities that are measured at fair value on a recurring basis:
			Fair Value As of
		Fair Value Hierarchy	31-Mar-15		26-Feb-15
	Interest rate swap liability	Level 2	$	5,845	$	6,000
	Of these amounts, $4 million is included in the Other Current Liabilities and $2 million is included in the Other Liabilities financial statement line items in the Balance Sheet. The notional amounts of derivative instruments in the Unaudited Consolidated Balance Sheet as of March 31, 2015 were $475 million. The notional amount represents the gross contract notional amount of the derivatives outstanding. The derivative instruments are comprised of $275 million of contracts effective December 31, 2014 which expire December 31, 2015, and $200 million of contracts effective December 31, 2015 which expire December 31, 2016. The other terms are as follows:
	Contract received:    Floating interest rate        LIBOR + 3.25%
	Contract pay:    Fixed interest rates        2.45% - 3.18%
	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 March 31, 2015, it could have been required to settle its obligations under the agreements at their termination value. As of March 31, 2015, the termination value related to these agreements is a net liability position of $6 million. As of March 31, 2015, the Company has not posted any collateral related to these agreements.

Restructuring_and_Integration_

Restructuring and Integration Costs	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Integration Costs	Restructuring and Integration Costs
	2015 Costs
	During the three months ended March 31, 2015 in conjunction with the integration of TASC, we incurred $10 million in restructuring costs, including costs related to workforce reduction which will be paid out over the next 12 months.
	2014 Costs
	During the year ended December 31, 2014 in conjunction with the integration of DRC, and our move to a customer focused model, we incurred $1 million in restructuring costs, including costs related to workforce reduction.
	2013 Costs
	During the fourth quarter of 2013, we classified several leased facilities as abandoned and recorded a charge of $8 million which will be amortized over the next six years. The accrued liability is amortized and reduces the current period expense as we make scheduled lease payments.
	The activity and balance of the restructuring liability account for the three months ended March 31, 2015 were as follows:
		Severance			Accrued Lease Fees			Total
		and Related
		Costs
	Balance as of December 31, 2013	$	337		$	7,533		$	7,870
	Additions	1,134			—			1,134
	Cash payments	(1,103		)	(1,497		)	(2,600		)
	Balance as of December 31, 2014	368			6,036			6,404
	Additions	10,499			—			10,499
	Cash payments	(326		)	(298		)	(624		)
	Balance as of March 31, 2015	$	10,541		$	5,738		$	16,279
	Amounts contained in the current liabilities line of our balance sheet as of March 31, 2015	$	10,541		$	1,192		$	11,733
	Amounts contained in the other liabilities line of our balance sheet as of March 31, 2015	$	—		$	4,546		$	4,546
	These expenses are contained within the selling, general and administrative expenses line in the accompanying Unaudited Consolidated Statement of Operations for the appropriate period.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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.
	We are currently cooperating with the U.S. government on several investigations from which civil or administrative proceedings have or could result and give rise to fines, penalties, compensatory and treble damages, restitution and/or forfeitures. 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. We are subject to claims from jurisdictions where we presently have or previously had operations for charges and fees such as non-income-related taxes. We accrue for these liabilities when they are probable and reasonably estimable. These accrued liabilities are increased or decreased based on claims, as new facts are determined which impact these liabilities, and final settlement or resolution could differ materially. 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 the consolidated balance sheets. Amounts recoverable from insurance contracts or third parties are recorded as assets when deemed probable. At December 31, 2014 and March 31, 2015, 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	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The effective tax rate for the three months ended March 31, 2015 was 31.0% as compared to 41.0% for the three months ended March 31, 2014. The decrease in the effective tax rate, which includes the effects of discrete items, was due to a favorable tax benefit in our joint venture offset by an increase for the nondeductible acquisition costs for the three months ended March 31, 2015 as compared to the three months ended March 31, 2014.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business: Engility Holdings, Inc. (Engility) through its predecessors, has provided mission critical services to the U.S. government for over six decades. Engility serves among other federal agencies, the U.S. Department of Defense (DoD), U.S. Department of Justice (DoJ), U.S. Agency for International Development (USAID), U.S. Department of State (DoS), Federal Aviation Administration (FAA), Department of Homeland Security (DHS), and allied foreign governments. With Engility's recent acquisition of TASC, Inc. (TASC) on February 26, 2015, Engility further diversified its portfolio to add leading positions with U.S. national security and public safety agencies, including the National Geospatial-Intelligence Agency (NGA), National Security Agency (NSA), Defense Intelligence Agency (DIA), and other intelligence community agencies. Engility also added space-related agencies such as the National Reconnaissance Organization (NRO), National Aeronautical and Space Administration (NASA), and U.S. Air Force. The acquisition of TASC also enhanced Engility's market position with DHS, Defense Threat Reduction Agency (DTRA), FAA, and Missile Defense Agency (MDA).
Principles of Consolidation and Combination 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. On January 31, 2014, we completed the acquisition of Dynamics Research Corporation (DRC) which is more fully described in Note 3 to the accompanying Unaudited Consolidated Financial Statements. On February 26, 2015, we completed the acquisition of TASC which is more fully described in Note 3 to the accompanying Unaudited Consolidated Financial Statements. These transactions were recorded using the purchase method of accounting; accordingly, DRC's and TASC's financial results are included in the Unaudited Consolidated Financial Statements for the periods subsequent to the acquisition.
	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 for the year ended December 31, 2014 (2014 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.
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 the allowable costs incurred during the period 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, the Company recognizes income when such fees are probable and estimable. 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 percentage-of-completion 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. Profits on fixed-price contracts result from the difference between incurred costs and revenue earned.
	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 the Company’s contracts, developing total revenue and cost at completion estimates requires 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 “out of pocket” costs that often include, but are not limited to, travel-related costs and telecommunications charges. The Company recognizes 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.
	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.
	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.
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 relate to the recoverability, useful lives and valuation of identifiable intangible assets and goodwill, income tax contingencies and revenue and expenses for certain revenue arrangements. Actual amounts may differ from these estimates and could differ materially.
Reporting Periods	Reporting Periods: Our fiscal year begins on January 1 and ends on December 31. Our fiscal quarters end on March 31, June 30, September 30, and December 31.
Earnings Per Share	Earnings per Share: Basic earnings per share (EPS) is computed by dividing net income by the weighted average number of common shares outstanding for the period. Diluted EPS reflects potential dilution that could occur if securities to issue common stock were exercised or converted into common stock. Diluted EPS includes the effect of the employee stock purchase plan, restricted stock units (RSU), stock options, performance shares and performance units calculated using the treasury stock method. For the three months ended March 31, 2015 and March 31, 2014, 671,602 shares and no shares were excluded from diluted EPS, respectively.
New Accounting Pronouncements	New Accounting Pronouncements
	In May 2014, the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 outlines a single comprehensive model for entities to use when accounting for revenue arising from contracts with customers and supersedes all current revenue recognition guidance, including industry-specific guidance. This new guidance is effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2016; early adoption is not permitted. Entities have the option of using either a full retrospective or a modified approach to adopt the guidance. This update could impact the timing and amounts of revenue recognized. On April 1, 2015, the FASB proposed deferring the effective date by one year to December 15, 2017 for annual periods beginning after that date.
	We are currently evaluating the effect that implementation of this update will have on our consolidated financial position and results of operations upon adoption.
	In June 2014, the FASB issued ASU No. 2014-12, Compensation - Stock Compensation (Topic 718) - Accounting for Share-based Payments when Terms of an award Provide That a Performance Target Could be Achieved after the Requisite Service Period. The Amendments in ASU 2014-12 require that a performance target that affects vesting and that could be achieved after the requisite service period be treated as a performance condition. ASU 2014-12 is effective for interim and annual reporting periods beginning after December 15, 2015, with early adoption permitted. We do not expect this pronouncement to have a material impact on our financial statements.
	In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern.  The guidance requires an entity to evaluate whether there are conditions or events, in the aggregate, that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued (or within one year after the financial statements are available to be issued when applicable) and to provide related footnote disclosures in certain circumstances.  The guidance is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter.  Early application is permitted.  We do not believe the adoption of this guidance will have a significant impact on our consolidated financial statements.
	In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest, which changes the presentation of debt issuance costs in financial statements. The amendments in this standard require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this standard. The guidance is effective for the annual period ending after December 15, 2016, and for annual and interim periods thereafter.  We do not believe the adoption of this guidance will have a significant impact on our consolidated financial statements.

Basis_of_Presentation_Tables

Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Earnings Per Share
		Three Months Ended
		March 31, 2015			March 31, 2014
	Net income (loss) attributable to Engility	$	(13,367	)	$	8,871
	Weighted average number of shares outstanding – Basic	24,379			16,993
	Dilutive effect of share-based compensation outstanding after application of the treasury stock method	—			901
	Weighted average number of shares – Diluted	24,379			17,894
	Earnings (loss) per share attributable to Engility
	Basic	$	(0.55	)	$	0.52
	Diluted	$	(0.55	)	$	0.5

Business_Acquisition_Tables

Business Acquisition (Tables)	3 Months Ended
	Mar. 31, 2015
Business Acquisition [Line Items]
Business Acquisition Pro Forma Information	The following pro forma results of operations have been prepared as though the acquisition of TASC had occurred on January 1, 2014. These pro forma results include adjustments for (1) amortization expense for the estimated identifiable intangible assets in the preliminary allocation of purchase price, (2) the removal of historical TASC amortization expense, (3) adjustments to conform TASC policies to Engility's policies related to the timing and recognition of certain contract revenue and costs, (4) the alignment of TASC’s financial calendar to that of Engility’s and 5) the removal of acquisition-related expenses incurred and recorded in each of TASC and Engility’s results of operations in the three months ended March 31, 2015, and a related adjustment to record such costs in the three months ended March 31, 2014.
	The pro forma results of operations also include adjustments to reflect the acquisition of DRC, which was acquired January 31, 2014, as though the acquisition occurred on January 1, 2013. These pro forma results include adjustments for (1) amortization expense for the identifiable intangible assets in the final purchase price allocation, (2) the removal of historical DRC amortization expense, and (3) the removal of acquisition-related expenses incurred and recorded on each of DRC and Engility’s results of operations in the three months ended March 31, 2014.
	This pro forma information does not purport to be indicative of the results of operations that would have been attained had the acquisitions been made as of January 1, 2014 and January 1, 2013 respectively, or of results of operations that may occur in the future.
		Three Months Ended
		March 31, 2015				March 31, 2014
	Revenue	$	561,935			$	637,300
	Operating income (loss)	26,801				(8,156		)
TASC
Business Acquisition [Line Items]
Summary of Preliminary Allocation of Purchase Price	We are in the process of finalizing the valuation of the TASC-related assets acquired and liabilities assumed, in particular those requiring significant judgment including evaluating lease values, liabilities, and reserves. The preliminary allocation of purchase price is as follows:
	Number of Engility shares issued				18,937,765
	Share price on February 26, 2015	$	46.45
	Dividend payable to Engility shareholders	11.434
	Value of Engility shares issued to TASC shareholders				$	35.016
	Equity consideration							$	663,125
	Cash							$	25,478
	Receivables							147,972
	Prepaid and deferred income taxes, current							22,106
	Other current assets							26,026
	Property, plant and equipment							15,835
	Deferred tax assets							177,889
	Other assets							5,096
	Current portion of long-term debt							(4,097		)
	Accounts payable, trade							(34,403		)
	Accrued employment costs							(92,396		)
	Accrued expenses							(32,520		)
	Advance payments and billings in excess of costs incurred							(18,004		)
	Deferred income taxes, current and income taxes payable							(247		)
	Other current liabilities							(31,301		)
	Long-term debt							(619,227		)
	Other long-term liabilities							(24,446		)
	Identifiable intangible assets							360,400
	Goodwill							738,964
								$	663,125
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The valuation of the identified intangible assets acquired is summarized below:
		Useful Life (years)
	Customer contractual relationships	15		$	335,700
	Contractual backlog	1		17,700
	Technology	15		7,000
	Total intangible assets			$	360,400
Dynamics Research Corporation
Business Acquisition [Line Items]
Summary of Preliminary Allocation of Purchase Price
	Cash consideration	$	207,250
	Receivables	$	43,246
	Other current assets	2,135
	Property, plant and equipment	8,604
	Other assets	5,985
	Accounts payable, trade	(15,436		)
	Accrued employment costs	(16,845		)
	Accrued expenses	(4,735		)
	Advance payments and billings in excess of costs incurred	(309		)
	Deferred income taxes, current and income taxes payable	1,208
	Other current liabilities	(4,041		)
	Income tax payable	(800		)
	Other long-term liabilities	(24,912		)
	Identifiable intangible assets	46,200
	Goodwill	166,950
		$	207,250
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The valuation of the identified intangible assets acquired is summarized below:
		Useful Life (years)
	Customer contractual relationships	16		$	42,100
	Contractual backlog	1		4,100
	Total intangible assets			$	46,200

Receivables_Tables

Receivables (Tables)	3 Months Ended
	Mar. 31, 2015
Receivables [Abstract]
Components of Contract Receivables	The components of contract receivables are presented in the table below.
		As of			As of
		March 31,			December 31,
		2015			2014
	Billed receivables	$	147,235		$	115,500
	Unbilled receivables	289,174			172,385
	Allowance for doubtful accounts	(1,671		)	(1,482		)
	Total receivables, net	$	434,738		$	286,403

Goodwill_and_Identifiable_Inta1

Goodwill and Identifiable Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
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.
				March 31, 2015								31-Dec-14
		Weighted Average Remaining Useful Life		Gross				Accumulated		Net		Gross		Accumulated		Net
				Carrying				Amortization		Carrying		Carrying		Amortization		Carrying
				Amount						Amount		Amount				Amount
		(in years)
	Customer contractual relationships	17		$	556,430			$	102,216	$	454,214	$	220,730	$	97,523	$	123,207
	Contractual Backlog	1		21,800				5,575		16,225		4,100		3,758		342
	Technology	15		7,000				36		6,964		—		—		—
	Total			$	585,230			$	107,827	$	477,403	$	224,830	$	101,281	$	123,549
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
		March 31, 2015				March 31, 2014
	Amortization expense	$	6,546			$	3,303

Defined_Benefit_Pension_Plan_T

Defined Benefit Pension Plan (Tables)	3 Months Ended
	Mar. 31, 2015
Postemployment Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	The components of net periodic pension income for the Pension Plan for the three months ended March 31, 2015 and 2014 are as follows:
		Three Months Ended
		March 31, 2015			31-Mar-14
	Interest cost on projected benefit obligation	$	991		$	652
	Expected return on plan assets	(1,466		)	(970		)
	Net loss amortization	49			—
	Net periodic pension expense (income)	$	(426	)	$	(318	)
	TASC Defined Benefit Plan
	Upon the closing of the TASC acquisition, we assumed TASC's defined benefit plan in which certain employees are eligible to participate based upon service with the TASC's prior parent. This plan offers two retirement programs, a Retiree Health Reimbursement Account Plan (RHRA) and a Cash Bonus Plan, which provide a restoration of certain pension benefits that would have been forfeited as a result of years of service and final average pay being frozen by TASC's prior parent. The liability of the TASC defined benefit plan was $21 million on the date of acquisition.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
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:
			Fair Value As of
		Fair Value Hierarchy	31-Mar-15		26-Feb-15
	Interest rate swap liability	Level 2	$	5,845	$	6,000

Restructuring_and_Integration_1

Restructuring and Integration Costs (Tables)	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Summary of Realignment Cost	The activity and balance of the restructuring liability account for the three months ended March 31, 2015 were as follows:
		Severance			Accrued Lease Fees			Total
		and Related
		Costs
	Balance as of December 31, 2013	$	337		$	7,533		$	7,870
	Additions	1,134			—			1,134
	Cash payments	(1,103		)	(1,497		)	(2,600		)
	Balance as of December 31, 2014	368			6,036			6,404
	Additions	10,499			—			10,499
	Cash payments	(326		)	(298		)	(624		)
	Balance as of March 31, 2015	$	10,541		$	5,738		$	16,279
	Amounts contained in the current liabilities line of our balance sheet as of March 31, 2015	$	10,541		$	1,192		$	11,733
	Amounts contained in the other liabilities line of our balance sheet as of March 31, 2015	$	—		$	4,546		$	4,546

Basis_of_Presentation_Addition

Basis of Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Non-controlling equity interest ownership percentage	50.10%
Shares excluded from diluted EPS (shares)	671,602	0

Basis_of_Presentation_Earnings

Basis of Presentation - Earnings Per Share (Detail) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net income (loss) attributable to Engility	($13,367)	$8,871
Weighted average number of shares outstanding - Basic (shares)	24,379	16,993
Dilutive effect of share-based compensation outstanding after application of the treasury stock method (shares)	0	901
Weighted average number of shares - Diluted (shares)	24,379	17,894
Earnings (loss) per share attributable to Engility
Basic (USD per share)	($0.55)	$0.52
Diluted (USD per share)	($0.55)	$0.50

Business_Acquisition_TASC_Acqu

Business Acquisition - TASC Acquisition (Details) (USD $)	0 Months Ended	3 Months Ended
	Feb. 26, 2015	Mar. 31, 2015	Mar. 31, 2014
	board_member
Business Acquisition [Line Items]
Common stock ownership, percent	99.00%
Dividends paid		$201,400,000	$0
Number of Board members eligible to be nominated	11
Number of Board members eligible to be nominated by Engility directors	7
Number of Board members eligible to be nominated, by Birch Partners	4
TASC
Business Acquisition [Line Items]
Number of employees	4,000
Common stock ownership, percent	52.00%
Number of Engility shares issued	18,937,765
Equity consideration	663,125,000
Debt assumed	623,000,000
Special dividend value	207,000,000
Dividend payable to Engility shareholders	11.434
Dividends payable		5,000,000
Common stock ownership, maximum percent. before consensus voting		30.00%
Revenue of acquiree since acquisition date		99,000,000
Pre-tax net income of acquiree since acquisition		6,000,000
Acquisition costs		$28,000,000
TASC | Minimum
Business Acquisition [Line Items]
Common stock ownership, percent required to consensus voting	21.00%
TASC | Maximum
Business Acquisition [Line Items]
Common stock ownership, percent required to consensus voting	21.50%
TASC | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P.
Business Acquisition [Line Items]
Number of Board members eligible to be nominated	4
TASC | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Minimum
Business Acquisition [Line Items]
Business combination, period in which ownership can not be transfered	1 year
Business combination, period in which limited ownership can be transfered	4 years
TASC | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Maximum
Business Acquisition [Line Items]
Business combination, period in which ownership can not be transfered	3 years
Business combination, period in which limited ownership can be transfered	6 years
TASC | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Scenario 1
Business Acquisition [Line Items]
Common stock ownership, percent	50.00%
Number of Board members eligible to be nominated	4
TASC | Birch Partners, LP And Kohlberg Kravis Roberts & Co. L.P. | Scenario 2
Business Acquisition [Line Items]
Common stock ownership, percent	25.00%
Number of Board members eligible to be nominated	2

Business_Acquisition_Purchase_

Business Acquisition - Purchase Price Allocation (Details) (USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Feb. 26, 2015	Jan. 31, 2014	Mar. 31, 2015	Dec. 31, 2014
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill			$1,383,518	$644,554
TASC
Business Combination, Consideration Transferred [Abstract]
Number of Engility shares issued	18,937,765
Share price (USD per share)	$46.45
Dividend payable to Engility shareholders	$11.43
Value of Engility shares issued to TASC shareholders (USD per share)	$35.02
Consideration transfered	663,125
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cash	25,478
Receivables	147,972
Prepaid and deferred income taxes, current	22,106
Other current assets	26,026
Property, plant and equipment	15,835
Deferred tax assets	177,889
Other assets	5,096
Current portion of long-term debt	-4,097
Accounts payable, trade	-34,403
Accrued employment costs	-92,396
Accrued expenses	-32,520
Advance payments and billings in excess of costs incurred	-18,004
Deferred income taxes, current and income taxes payable	-247
Other current liabilities	-31,301
Long-term debt	-619,227
Other long-term liabilities	-24,446
Identifiable intangible assets	360,400
Goodwill	738,964
Net assets acquired	663,125
Dynamics Research Corporation
Business Combination, Consideration Transferred [Abstract]
Consideration transfered		207,250
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Receivables		43,246
Other current assets		2,135
Property, plant and equipment		8,604
Other assets		5,985
Accounts payable, trade		-15,436
Accrued employment costs		-16,845
Accrued expenses		-4,735
Advance payments and billings in excess of costs incurred		-309
Deferred income taxes, current and income taxes payable		1,208
Other current liabilities		-4,041
Income tax payable		-800
Other long-term liabilities		-24,912
Identifiable intangible assets		46,200
Goodwill		166,950
Net assets acquired		$207,250

Business_Acquisition_Intangibl

Business Acquisition - Intangible Assets (Details) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Feb. 26, 2015	Jan. 31, 2014
TASC
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets acquired in a business combination	$360,400
TASC | Customer contractual relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life (years)	15 years
Finite lived intangible assets acquired in a business combination	335,700
TASC | Contractual backlog
Finite-Lived Intangible Assets [Line Items]
Useful Life (years)	1 year
Finite lived intangible assets acquired in a business combination	17,700
TASC | Technology
Finite-Lived Intangible Assets [Line Items]
Useful Life (years)	15 years
Finite lived intangible assets acquired in a business combination	7,000
Dynamics Research Corporation
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets acquired in a business combination		46,200
Dynamics Research Corporation | Customer contractual relationships
Finite-Lived Intangible Assets [Line Items]
Useful Life (years)		16 years
Finite lived intangible assets acquired in a business combination		42,100
Dynamics Research Corporation | Contractual backlog
Finite-Lived Intangible Assets [Line Items]
Useful Life (years)		1 year
Finite lived intangible assets acquired in a business combination		$4,100

Business_Acquisition_Pro_Forma

Business Acquisition - Pro Forma (Details) (TASC, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
TASC
Business Acquisition [Line Items]
Revenue	$561,935	$637,300
Net income attributable to Engility	$26,801	($8,156)

Business_Acquisition_DRC_Acqui

Business Acquisition - DRC Acquisition (Details) (Dynamics Research Corporation, USD $)	0 Months Ended	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jan. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Dynamics Research Corporation
Business Acquisition [Line Items]
Price per share (USD per share)	$11.50
Aggregate cash purchase price	$207
Debt assumed in a business combination	86
Revenue of acquiree since acquisition date			39
Pre-tax net income of acquiree since acquisition		$1

Receivables_Components_of_Cont

Receivables - Components of Contract Receivables (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Receivables [Abstract]
Billed receivables	$147,235	$115,500
Unbilled receivables	289,174	172,385
Allowance for doubtful accounts	-1,671	-1,482
Total receivables, net	$434,738	$286,403

Goodwill_and_Identifiable_Inta2

Goodwill and Identifiable Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Feb. 26, 2015
Goodwill [Line Items]
Goodwill	$1,383,518,000	$644,554,000
TASC
Goodwill [Line Items]
Goodwill			738,964,000
Goodwill acquired in a business combination	$739,000,000

Goodwill_and_Identifiable_Inta3

Goodwill and Identifiable Intangible Assets - Information on Identifiable Intangible Assets (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$585,230	$224,830
Accumulated Amortization	107,827	101,281
Net Carrying Amount	477,403	123,549
Customer contractual relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	17 years
Gross Carrying Amount	556,430	220,730
Accumulated Amortization	102,216	97,523
Net Carrying Amount	454,214	123,207
Contractual backlog
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	1 year
Gross Carrying Amount	21,800	4,100
Accumulated Amortization	5,575	3,758
Net Carrying Amount	16,225	342
Technology
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Useful Life	15 years
Gross Carrying Amount	7,000	0
Accumulated Amortization	36	0
Net Carrying Amount	$6,964	$0

Goodwill_and_Identifiable_Inta4

Goodwill and Identifiable Intangible Assets - Amortization Expense Recorded for Identifiable Intangible Assets (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$6,546	$3,303

ShareBased_Compensation_Effect

Share-Based Compensation - Effects of TASC Transaction on Engility Equity Awards (Details)	0 Months Ended	3 Months Ended
	Feb. 26, 2015	Mar. 31, 2014
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting as a result of change in control	364,983
Restricted Stock Units | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares in which vesting was waived	229,166
Restricted Stock Units | Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vesting as a result of change in control	43,950
Shares in which vesting was waived	11,790
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	127.00%	200.00%
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	100.00%	0.00%

ShareBased_Compensation_Additi

Share-Based Compensation - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended
	Feb. 26, 2015	Mar. 31, 2015	Mar. 31, 2014
Performance Retention Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		212,963
Shares granted at maximum performance level		425,926
Weighted average share price (USD per share)		$32.82
Vesting period		3 years
Performance period		3 years
Performance Retention Award | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount		50.00%
Performance Retention Award | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount		200.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		191,848	102,961
Shares granted at maximum performance level		431,658	205,922
Weighted average share price (USD per share)		$32.29	$56.14
Vesting period	3 years
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	100.00%		0.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percent of the target grant amount	127.00%		200.00%
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period			72,869
Restricted Stock Units | Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		127,899
Weighted average share price (USD per share)		$32.82	$44.33
Performance period		3 years
RSUs granted that vest ratably over the term of three years from the grant date			68,633
Stock vest on first anniversary			25.00%
Stock vest on second anniversary			25.00%
Stock vest on third anniversary			50.00%
Restricted Stock Units | Non-management Members Of The Board Of DIrectors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted in the period		2,482
Weighted average share price (USD per share)		$32.82
Restricted Stock Units Rsu Cliff Vest | Non-executive Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted that cliff vest on first anniversary of grant date			4,236

Defined_Benefit_Pension_Plan_D

Defined Benefit Pension Plan (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 26, 2015
Postemployment Benefits [Abstract]
Interest cost on projected benefit obligation	$991,000	$652,000
Expected return on plan assets	-1,466,000	-970,000
Net loss amortization	49,000	0
Net periodic pension expense (income)	-426,000	-318,000
Acquired pension plan balance			$21,000,000

Debt_Details

Debt (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 26, 2015	Aug. 09, 2013
Debt Instrument [Line Items]
Gross borrowings from issuance of long-term debt	$585,000,000	$75,000,000
Credit Facility 2015
Debt Instrument [Line Items]
Line of credit, amount outstanding	1,231,000,000
Quarterly principal payments percentage	0.25%
Maximum net leverage ratio	6.75
Maximum net leverage ratio, requirement one	6.5
Maximum net leverage ration, requirement two	6
Maximum net leverage ratio, requirement three	5.5
Maximum net leverage ratio, requirement four	5
Maximum net leverage ratio, requirement five	4.5
Net leverage ratio	4.76
Debt issuance costs	1,000,000
Average outstanding loan amount	662,000,000
Weighted average interest rate	7.43%
Long-term debt	1,206,000,000
Line of credit, remaining borrowing capacity	106,000,000
Letters of credit outstanding	4,000,000
Credit Facility 2015 | Federal Funds Effective Rate
Debt Instrument [Line Items]
Basis spread on variable rate			0.50%
Credit Facility 2015 | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Variable Rate Floor			1.00%
First Lien Credit Agreement | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	6.00%
First Lien Credit Agreement | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	5.00%
Second Lien Credit Agreement
Debt Instrument [Line Items]
Stated interest rate			12.00%
2013 Credit Facility
Debt Instrument [Line Items]
Debt issuance costs	5,000,000
Sublimit for letters of credit				50,000,000
Line of credit facility borrowing capacity available for swing line loans under revolving credit facility				25,000,000
Line of credit facility accordion feature, additional borrowing capacity				150,000,000
Secured Debt | Original First Lien Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			395,000,000
Secured Debt | Incremental First Lien Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			435,000,000
Secured Debt | Incremental Second Lien Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			150,000,000
Secured Debt | 2013 Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				275,000,000
Average outstanding loan amount		320,000,000
Weighted average interest rate		2.95%
Revolving Credit Facility | First Lien Credit Agreement and Second Lien Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			50,000,000
Revolving Credit Facility | Additional Senior Secured First Lien Revolving Credit Capacity
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			65,000,000
Revolving Credit Facility | Original Second Lien Term Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			250,000,000
Revolving Credit Facility | 2013 Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				325,000,000
Promissory Note
Debt Instrument [Line Items]
Gross borrowings from issuance of long-term debt			585,000,000

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Liabilites Measured on a Recurring Basis (Details) (Recurring, Level 2, USD $)	Mar. 31, 2015	Feb. 26, 2015
In Thousands, unless otherwise specified
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liability	$5,845	$6,000

Fair_Value_Measurements_Narrat

Fair Value Measurements Narrative (Details) (USD $)	Mar. 31, 2015	Feb. 26, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount	$475,000,000
Interest Rate Swap Effective December 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount	275,000,000
Interest Rate Swap Effective December 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, notional amount	200,000,000
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fixed interest rate	2.45%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, fixed interest rate	3.18%
London Interbank Offered Rate (LIBOR)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, basis spread on variable interest rate	3.25%
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liability	5,845,000	6,000,000
Other Current Liabilities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liability	4,000,000
Other Liabilities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate swap liability	$2,000,000

Restructuring_and_Integration_2

Restructuring and Integration Costs (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Restructuring costs			$1,000,000
Lease abandonment charge		8,000,000
Lease abandonment charger amortization period		6 years
Restructuring Cost and Reserve [Line Items]
Beginning Balance	6,404,000		7,870,000
Additions	10,499,000		1,134,000
Cash payments	-624,000		-2,600,000
Ending Balance	16,279,000	7,870,000	6,404,000
Other Current Liabilities
Restructuring Cost and Reserve [Line Items]
Ending Balance	11,733,000
Other Liabilities
Restructuring Cost and Reserve [Line Items]
Ending Balance	4,546,000
Severance and Related Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance	368,000		337,000
Additions	10,499,000		1,134,000
Cash payments	-326,000		-1,103,000
Ending Balance	10,541,000		368,000
Severance and Related Costs | Other Current Liabilities
Restructuring Cost and Reserve [Line Items]
Ending Balance	10,541,000
Accrued Lease Fees
Restructuring Cost and Reserve [Line Items]
Beginning Balance	6,036,000		7,533,000
Additions	0		0
Cash payments	-298,000		-1,497,000
Ending Balance	5,738,000		6,036,000
Accrued Lease Fees | Other Current Liabilities
Restructuring Cost and Reserve [Line Items]
Ending Balance	1,192,000
Accrued Lease Fees | Other Liabilities
Restructuring Cost and Reserve [Line Items]
Ending Balance	$4,546,000

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Effective income tax rate	31.00%	41.00%