Mantech International (MANT) 10-K 23 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 21, 2018	Jun. 30, 2017
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Trading Symbol	MANT
Entity Registrant Name	MANTECH INTERNATIONAL CORP
Entity Central Index Key	892,537
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,060
Class A Common Stock [Member]
Entity Information [Line Items]
Common Stock, Shares Outstanding		26,040,507
Class B Common Stock [Member]
Entity Information [Line Items]
Common Stock, Shares Outstanding		13,189,245

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 9,451,000	$ 64,936,000
Receivables—net	311,410,000	320,677,000
Prepaid expenses and other	46,207,000	34,423,000
Contractual inventory	96,000	1,277,000
Total Current Assets	367,164,000	421,313,000
Goodwill	1,084,560,000	955,874,000
Other intangible assets—net	194,348,000	154,931,000
Property and equipment—net	46,082,000	23,121,000
Employee supplemental savings plan assets	33,555,000	29,383,000
Investments	11,843,000	11,691,000
Other assets	6,923,000	2,151,000
TOTAL ASSETS	1,744,475,000	1,598,464,000
LIABILITIES
Accounts payable and accrued expenses	122,405,000	108,888,000
Accrued salaries and related expenses	87,064,000	70,768,000
Billings in excess of revenue earned	18,816,000	11,998,000
Total Current Liabilities	228,285,000	191,654,000
Long term debt, net of current portion	31,000,000	0
Deferred income taxes—non-current	97,194,000	122,081,000
Accrued retirement	34,517,000	30,581,000
Other long-term liabilities	10,505,000	12,481,000
TOTAL LIABILITIES	401,501,000	356,797,000
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY
Additional paid-in capital	492,030,000	471,906,000
Treasury stock	(9,158,000)	(9,158,000)
Retained earnings	860,027,000	778,710,000
Accumulated other comprehensive loss	(320,000)	(181,000)
TOTAL STOCKHOLDERS' EQUITY	1,342,974,000	1,241,667,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	1,744,475,000	1,598,464,000
Class A Common Stock [Member]
STOCKHOLDERS' EQUITY
Common stock	263,000	258,000
TOTAL STOCKHOLDERS' EQUITY	263,000	258,000
Class B Common Stock [Member]
STOCKHOLDERS' EQUITY
Common stock	132,000	132,000
TOTAL STOCKHOLDERS' EQUITY	$ 132,000	$ 132,000

Consolidated Balance Sheets Par

Consolidated Balance Sheets Parenthetical - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Treasury Stock, Shares	244,113	244,113
Class A Common Stock [Member]
Common Stock, Par Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	150,000,000	150,000,000
Common Stock, Shares Issued	26,285,773	25,795,973
Common Stock, Shares Outstanding	26,041,660	25,551,860
Class B Common Stock [Member]
Common Stock, Par Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	50,000,000	50,000,000
Common Stock, Shares Issued	13,189,245	13,190,745
Common Stock, Shares Outstanding	13,189,245	13,190,745

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUES	$ 1,717,018	$ 1,601,596	$ 1,550,117
Cost of services	1,463,599	1,369,775	1,320,697
General and administrative expenses	155,225	140,858	144,534
OPERATING INCOME	98,194	90,963	84,886
Interest expense	(1,375)	(1,097)	(1,193)
Interest income	104	121	160
Other income (expense), net	319	83	1,501
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND EQUITY METHOD INVESTMENTS	97,242	90,070	85,354
Benefit (provision) for income taxes	16,859	(33,786)	(34,366)
Equity in gains of unconsolidated subsidiaries	40	107	139
NET INCOME	$ 114,141	$ 56,391	$ 51,127
Class A Common Stock [Member]
BASIC EARNINGS PER SHARE:
Basic earnings per share	$ 2.94	$ 1.48	$ 1.36
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	2.91	1.47	1.36
Class B Common Stock [Member]
BASIC EARNINGS PER SHARE:
Basic earnings per share	2.94	1.48	1.36
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	$ 2.91	$ 1.47	$ 1.36

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 114,141	$ 56,391	$ 51,127
OTHER COMPREHENSIVE INCOME (LOSS):
Actuarial gain (loss) on defined benefit pension plans, net of tax	(84)	(29)	84
Translation adjustments, net of tax	(55)	(43)	14
Total other comprehensive income (loss)	(139)	(72)	98
COMPREHENSIVE INCOME	$ 114,002	$ 56,319	$ 51,225

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($)	Total	Common Stock, Class A	Common Stock, Class B	Additional Paid-In Capital	Treasury Stock, at cost	Retained Earnings	Accumulated Other Comprehensive Loss
At beginning of year at Dec. 31, 2014		$ 244,000	$ 132,000	$ 428,895,000	$ (9,158,000)	$ 734,873,000	$ (207,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises		3,000		7,865,000
Stock compensation expense				4,379,000
Tax deficiency from the exercise of stock options	$ 3,000,000			(2,971,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09				0
Net income	51,127,000					51,127,000
Dividends						(31,543,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09						0
Actuarial gain (loss) on defined benefit pension plans, net of tax	84,000						84,000
Translation adjustments, net of tax	14,000						14,000
At end of year at Dec. 31, 2015	1,183,737,000	247,000	132,000	438,168,000	(9,158,000)	754,457,000	(109,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises		11,000		30,551,000
Stock compensation expense				3,323,000
Tax deficiency from the exercise of stock options	100,000			(136,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09				0
Net income	56,391,000					56,391,000
Dividends						(32,138,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09						0
Actuarial gain (loss) on defined benefit pension plans, net of tax	(29,000)						(29,000)
Translation adjustments, net of tax	(43,000)						(43,000)
At end of year at Dec. 31, 2016	1,241,667,000	258,000	132,000	471,906,000	(9,158,000)	778,710,000	(181,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises		5,000		13,619,000
Stock compensation expense				6,319,000
Tax deficiency from the exercise of stock options				0
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09				186,000
Net income	114,141,000					114,141,000
Dividends						(32,709,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2016-09						(115,000)
Actuarial gain (loss) on defined benefit pension plans, net of tax	(84,000)						(84,000)
Translation adjustments, net of tax	(55,000)						(55,000)
At end of year at Dec. 31, 2017	$ 1,342,974,000	$ 263,000	$ 132,000	$ 492,030,000	$ (9,158,000)	$ 860,027,000	$ (320,000)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES:
Net income	$ 114,141,000	$ 56,391,000	$ 51,127,000
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	33,792,000	30,191,000	30,276,000
Deferred income taxes	(24,815,000)	18,254,000	30,553,000
Stock-based compensation	6,319,000	3,323,000	4,379,000
(Gain) loss on sale and retirement of property and equipment	76,000	(12,000)	(656,000)
Equity in gains of unconsolidated subsidiaries	(40,000)	(107,000)	(139,000)
Excess tax benefits from the exercise of stock options	0	(1,656,000)	(73,000)
Gain on disposition of business	0	0	(1,692,000)
Change in assets and liabilities—net of effects from acquired businesses:
Receivables-net	18,643,000	(5,611,000)	82,727,000
Prepaid expenses and other	(7,422,000)	(10,641,000)	(4,990,000)
Contractual inventory	1,181,000	(1,277,000)	0
Employee supplemental savings plan asset	(4,172,000)	(1,826,000)	4,184,000
Accounts payable and accrued expenses	(541,000)	(162,000)	(44,103,000)
Accrued salaries and related expenses	13,095,000	6,926,000	2,703,000
Billings in excess of revenue earned	1,177,000	(687,000)	913,000
Accrued retirement	3,936,000	704,000	(2,927,000)
Other	(2,412,000)	1,954,000	1,601,000
Net cash flow from operating activities	152,958,000	95,764,000	153,883,000
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Acquisition of businesses-net of cash acquired	(177,193,000)	(60,556,000)	(101,556,000)
Purchases of property and equipment	(31,118,000)	(7,662,000)	(5,202,000)
Investment in capitalized software for internal use	(7,744,000)	(2,748,000)	(1,025,000)
Deferred contract costs	(2,877,000)	0	0
Payments to acquire investments	(110,000)	(1,183,000)	(4,500,000)
Proceeds from sale of property and equipment	3,000	17,000	696,000
Transaction costs for disposition of business	0	0	(1,174,000)
Proceeds from sale of investment	0	0	13,000
Net cash flow from (used in) investing activities	(219,039,000)	(72,132,000)	(112,748,000)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Borrowings under revolving credit facility	136,500,000	0	163,200,000
Repayments under revolving credit facility	(105,500,000)	0	(163,200,000)
Dividends paid	(32,705,000)	(32,139,000)	(31,543,000)
Proceeds from exercise of stock options	13,624,000	30,562,000	7,868,000
Debt issuance costs	(1,323,000)	(89,000)	0
Excess tax benefits from the exercise of stock options	0	1,656,000	73,000
Net cash flow from (used in) financing activities	10,596,000	(10,000)	(23,602,000)
NET CHANGE IN CASH AND CASH EQUIVALENTS	(55,485,000)	23,622,000	17,533,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	64,936,000	41,314,000	23,781,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	9,451,000	64,936,000	41,314,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest	1,166,000	983,000	1,203,000
Noncash investing and financing activities:
Capital expenditures incurred but not yet paid	1,345,000	325,000	0
Deferred contract costs incurred but not yet paid	$ 872,000	$ 0	$ 0

Description of the Business (No

Description of the Business (Notes)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business [Text Block]	Description of the Business ManTech International Corporation (depending on the circumstances, “ManTech” “Company” “we” “our” “ours” or “us”) provide mission-focused technology solutions and services for U.S. defense, intelligence community and federal civilian agencies. Now in our 50th year, we excel in full-spectrum cyber, data collection & analytics, enterprise IT, systems engineering and software application development solutions that support national and homeland security.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Notes)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies Principles of Consolidation -Our consolidated financial statements include the accounts of ManTech International Corporation, subsidiaries we control and variable interest entities that are required to be consolidated. All intercompany accounts and transactions have been eliminated. Use of Accounting Estimates -We prepare our consolidated financial statements in conformity with U.S. GAAP, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates involve judgments with respect to, among other things, various future economic factors that are difficult to predict and are beyond the control of us. Therefore, actual amounts could differ from these estimates. Revenue Recognition -We derive the majority of our revenues from cost-plus-fixed-fee, cost-plus-award-fee, fixed-price and time-and-materials contracts. Revenues for cost-reimbursable contracts are recorded as reimbursable costs are incurred, including an estimated share of the applicable contractual fees earned. For performance-based fees under cost-reimbursable contracts, we recognize the relevant portion of the expected fee to be awarded by the customer at the time such fee can be reasonably estimated, based on factors such as our prior award experience and communications with the customer regarding performance, or upon approval by the customer. For time-and-materials contracts, revenues are recognized to the extent of billable rates times hours delivered plus materials and other reimbursable costs incurred. For long-term fixed-price contracts, revenues are recognized at a rate per unit as the units are delivered or by other methods to measure services provided. Revenues from other long-term fixed-price contracts are recognized ratably over the contract period or by other appropriate methods to measure services provided. Contract costs are expensed as incurred except for certain limited long-term contracts noted below. For long-term contracts, specifically described in the scope section of ASC 605-35 , Revenue Recognition - Construction-Type and Production-Type Contracts , we apply the percentage of completion method. Under the percentage of completion method, income is recognized at a consistent profit margin over the period of performance based on estimated profit margins at completion of the contract. This method of accounting requires estimating the total revenues and total contract cost at completion of the contract. During the performance of long-term contracts, these estimates are periodically reviewed and revisions are made as required using the cumulative catch-up method of accounting. The impact on revenues and contract profit as a result of these revisions is included in the periods in which the revisions are made. This method can result in the deferral of costs or the deferral of profit on these contracts. Because we assume the risk of performing a fixed-price contract at a set price, the failure to accurately estimate ultimate costs or to control costs during performance of the work could result, and in some instances has resulted, in reduced profits or losses for such contracts. Estimated losses on contracts at completion are recognized when identified. In certain circumstances, revenues are recognized when contract amendments have not been finalized. Cost of Services -Cost of services consists primarily of compensation expenses for program personnel, the fringe benefits associated with this compensation and other direct expenses incurred to complete programs, including cost of materials and subcontractor efforts. General and Administrative Expenses- General and administrative expenses include the salaries and wages, plus associated fringe benefits of our employees not performing work directly for customers, and associated facilities costs. Among the functions covered by these costs are corporate business development, bid and proposal, contracts administration, finance and accounting, legal, corporate governance and executive and senior management. In addition, we include stock-based compensation, as well as depreciation and amortization expenses related to the general and administrative function. We recognize interest related to unrecognized tax benefits within interest expense and penalties related to unrecognized tax benefits in general and administrative expenses. We classify indirect costs incurred as cost of services and general and administrative expenses in the same manner as such costs are defined in our disclosure statements under U.S. Government Cost Accounting Standards. Cash and Cash Equivalents -For the purpose of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks and short-term investments with maturity dates of three months or less at the date of purchase. Property and Equipment -Property and equipment are recorded at original cost to us. Upon sale or retirement, the costs and related accumulated depreciation or amortization are eliminated from the respective accounts and any resulting gain or loss is included in income. Maintenance and repairs are charged to expense as incurred. Depreciation and Amortization Method -Furniture and office equipment are depreciated using the straight-line method with estimated useful lives ranging from one to seven years . Leasehold improvements are amortized using the straight-line method over the shorter of the asset's useful life or the term of the lease. Goodwill -The purchase price of an acquired business is allocated to the tangible assets, financial assets and separately recognized intangible assets acquired less liabilities assumed based upon their respective fair values, with the excess recorded as goodwill. We review goodwill at least annually for impairment, or whenever events or circumstances indicate that the carrying value of long-lived assets may not be fully recoverable. Other Intangible Assets -Contract rights and other intangible assets are amortized primarily using the pattern of benefits method over periods ranging from one to twenty-five years . We account for the cost of computer software developed or obtained for internal use in accordance with ASC 350-985 , Intangibles - Goodwill and Other - Software . These capitalized software costs are included in other intangible assets, net. We account for software development costs related to software products for sale, lease or otherwise marketed in accordance with ASC 985-20 , Software - Costs of Software to Be Sold, Leased, or Marketed . For projects fully funded by us, development costs are capitalized from the point of demonstrated technological feasibility until the point in time that the product is available for general release to customers. Once the product is available for general release, capitalized costs are amortized based on units sold or on a straight-line basis over a five -year period or other such shorter period as may be required. Impairment of Long-Lived Assets- Whenever events or changes in circumstances indicate that the carrying amount of long-lived assets may not be fully recoverable, we evaluate the probability that future undiscounted net cash flows will be less than the carrying amount of the assets. If any impairment were indicated as a result of this review, we would recognize a loss based on the amount by which the carrying amount exceeds the estimated fair value. Employee Supplemental Savings Plan (ESSP) Assets -We maintain several non-qualified defined contribution supplemental retirement plans for certain key employees that are accounted for in accordance with ASC 710-10-05 , Compensation - General - Deferred Compensation - Rabbi Trust , as the underlying assets are held in rabbi trusts with investments directed by the respective employee. A rabbi trust is a grantor trust generally set up to fund compensation for a select group of management and the assets of this trust are available to satisfy the claims of general creditors in the event of bankruptcy of us. The assets held by the rabbi trusts are recorded at cash surrender value in our consolidated financial statements as ESSP assets with a related liability to employees recorded as a deferred compensation liability in accrued retirement. Billings In Excess of Revenue Earned -We receive advances and milestone payments from customers that exceed the revenues earned to date. We classify such items as current liabilities. Stock-based Compensation -We account for stock-based compensation in accordance with ASC 718 , Compensation - Stock Compensation , which requires the use of a valuation model to calculate the fair value of stock-based awards. We have elected to use the Black-Scholes-Merton pricing model to determine fair value of stock options on the dates of grant for our stock options. The fair value is included in operating expenses or capitalized, as appropriate, straight-line over the period in which service is provided in exchange for the award. The grant date fair value of the restricted stock is equal to the closing market price of our common stock on the date of grant. The compensation expense for restricted stock is recognized over the service period and is based on the grant date fair value of the shares. The grant date fair value of the restricted stock unit (RSU) is equal to the closing market price of our common stock on the grant date less the present value of dividends expected to be awarded during the service period. We recognize the grant date fair value of RSUs of shares we expect to issue as compensation expense ratably over the requisite service period. We account for forfeitures as they occur. Income Taxes -We account for income taxes in accordance with ASC 740 , Income Taxes . Under this method, deferred income taxes are determined based on the estimated future tax effects of differences between the financial statement and tax bases of assets and liabilities given the provisions of enacted tax laws. Deferred income tax provisions and benefits are based on changes to the assets or liabilities from year-to-year. In providing for deferred taxes, we consider tax regulations of the jurisdictions in which we operate, estimates of future taxable income and available tax planning strategies. If tax regulations, operating results or the ability to implement tax-planning strategies vary, adjustments to the carrying value of deferred tax assets and liabilities may be required. Valuation allowances are recorded related to deferred tax assets based on the “more likely than not” criteria. We recognize the financial statement benefit of a tax position only after determining that the relevant tax authority would “more likely than not” sustain the position following an audit. For tax positions meeting the “more likely than not” threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority. Foreign-Currency Translation -All assets and liabilities of foreign subsidiaries are translated into U.S. dollars at fiscal year-end exchange rates. Income and expense items are translated at average monthly exchange rates prevailing during the fiscal year. The resulting translation adjustments are recorded as a component of accumulated other comprehensive income (loss). Comprehensive Income (Loss) -Comprehensive income (loss) consists of net income; translation adjustments, net of tax; and actuarial gain (loss) on defined benefit pension plan, net of tax. Fair Value of Financial Instruments -The carrying value of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair value because of the short-term nature of these amounts. Variable Interest Entities (VIEs) -We determine whether we have a controlling financial interest in a VIE. The reporting entity with a variable interest or interest that provides the reporting entity with a controlling financial interest in a VIE will have both (a) the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. We have one entity that has been consolidated as a VIE. The purpose of the entity is to perform on certain U.S. Navy contracts. The maximum amount of loss we are exposed to as of December 31, 2017 was not material to our consolidated financial statements. Investments -Investments where we have the ability to exercise significant influence, but we do not control, are accounted for under the equity method of accounting and are included in other assets on our consolidated balance sheets. Significant influence typically exists if we have a 20% to 50% ownership interest in the investee. Under this method of accounting, our share of the net earnings or losses of the investee is included in equity in earnings or losses of unconsolidated subsidiaries on our consolidated statement of income. Investments where we have less than 20% ownership interest in the investee and lack the ability to exercise significant influence are accounted for under the cost method. Under the cost method, we recognize our investment in the stock of an investee as an asset. The investment is measured initially at cost. We recognize as income dividends received that are distributed from net accumulated earnings. Dividends received in excess of earnings are considered a return of investment and are recorded as reductions of costs of the investment. Impairment is assessed at the individual investment level. An investment is impaired if the fair value of the investment is less than its costs. If it is determined that the impairment is other than temporary, then an impairment loss is recognized in earnings. The fair value of the investment would become the new cost basis of the investment and will not be adjusted for subsequent recoveries in fair value. Business Combinations- The accounting for our business combinations consists of allocating the purchase price to tangible and intangible assets acquired and liabilities assumed based on their estimated fair values, with the excess recorded as goodwill. We have up to one year from the acquisition date to use information as of each acquisition date to adjust the fair value of the acquired assets and liabilities, which may result in material changes to their recorded values with an offsetting adjustment to goodwill. Recently Adopted ASUs On January 1, 2017, we adopted Accounting Standards Update (ASU) 2016-09, Compensation - Stock Compensation (Topic 718) . The changes in the ASU were adopted prospectively. The ASU requires all excess tax benefits or deficiencies to be recognized as income tax expense or benefit in the consolidated statement of income. Previously, excess tax benefits and deficiencies were recorded as a component of paid-in capital. For the years ended December 31, 2016 and 2015, we recorded $0.1 million and $3.0 million to paid-in capital for the net tax deficiencies related to the exercise of stock options, vested cancellations and the vesting of restricted stock. For the year ended December 31, 2017 , we recorded a net tax benefit of $2.7 million to income tax expense related to the exercise of stock options, vested cancellations and the vesting of restricted stock. The ASU allows a policy election to account for forfeitures as they occur verses requiring a forfeiture estimate. We have elected to account for forfeitures when they occur. Upon transition we recognized a cumulative-effect adjustment to retained earnings of $0.2 million related to previously estimated forfeitures. Under the ASU, excess tax benefits are no longer presented as financing activities in the statement of cash flows. The change in the presentation in the statement of cash flows was applied prospectively beginning January 1, 2017. Recently Issued But Not Yet Adopted ASUs On May 10, 2017, Financial Accounting Standards Board (FASB) has issued Accounting Standards Update (ASU) 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting , which seeks to provide clarity, reduce diversity in practice and reduce cost and complexity when applying the guidance in ASC 718, Compensation—Stock Compensation , regarding a change to the terms or conditions of a share-based payment award. ASU 2017-09 provides guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC 718. Specifically, an entity is to account for the effects of a modification, unless all of the following are satisfied: (1) the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; (2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and (3) the classification of the modified award as an equity instrument or as a liability instrument is the same as the classification of the original award immediately before the original award is modified. The current disclosure requirements in ASC 718 apply regardless of whether an entity is required to apply modification accounting under the amendments in ASU 2017-09. The amendments are effective for annual periods, and for interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period, for reporting periods for which financial statements have not yet been issued. We do not expect the adoption of this ASU to have a material effect on our consolidated financial statements. On January 26, 2017, the FASB has issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , which simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in this ASU, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. Finally, this ASU amends the Overview and Background sections of the ASC as part of the FASB’s initiative to unify and improve such sections across Topics and Subtopics. Public entities that are SEC filers should adopt the amendments in this ASU prospectively for their annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. Note that early adoption is permitted for all entities for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We will continue to evaluate the effects of this ASU in conjunction with our goodwill impairment tests. On January 5, 2017, the FASB has issued ASU 2017-01, Business Combinations (Topic 805)—Clarifying the Definition of a Business , which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. Under the current implementation guidance in Topic 805, there are three elements of a business: inputs, processes and outputs. While an integrated set of assets and activities (collectively, a “set”) that is a business usually has outputs, outputs are not required to be present. Additionally, all of the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs. The amendments in ASU 2017-01 provide a screen to determine when a set is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in this ASU (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. Finally, the amendments in this ASU narrow the definition of the term “output” so that the term is consistent with the manner in which outputs are described in Topic 606. The amendments are effective for annual periods beginning after December 15, 2017, including interim periods within those periods, with early adoption permissible. We do not expect this ASU to have a material effect on our consolidated financial statements. On August 26, 2016, the FASB issued ASU 2016-15— Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . This ASU addresses the following eight specific cash flow issues: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies (including bank-owned life insurance policies); distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The amendments in ASU 2016-15 become effective for fiscal years that start after December 15, 2017. We plan to apply it retrospectively to all periods presented in our quarterly and annual reports on Form 10-Q and Form 10-K. We plan to apply the equity method of accounting for applicable investments. Therefore, we will make an accounting policy election to classify distributions received from equity method investees using the cumulative earnings approach. Distributions received are considered returns on investment and classified as cash inflows from operating activities, unless the investor’s cumulative distributions received less distributions received in prior periods that were determined to be returns of investment exceed cumulative equity in earnings recognized by the investor (as adjusted for amortization of basis differences). When such an excess occurs, the current-period distribution up to this excess is considered a return of investment and should be classified as cash inflows from investing. We do not expect this ASU to have a material effect on our consolidated financial statements. On February 25, 2016, the FASB issued ASU 2016-02— Leases (Topic 842) . The amendments in this ASU create Topic 842 , Leases , and supersede the leases requirements in Topic 840, Leases . The objective of Topic 842 is to establish the principles that lessees and lessors should apply to report useful information to users of financial statements about the amount, timing and uncertainty of cash flows arising from a lease. This ASU is effective for public entities for annual periods after December 15, 2018, and interim periods therein. Early adoption is permitted for all entities. We are currently evaluating methods of adoption as well as the effect on our consolidated financial statements. However, it is expected to increase total assets and total liabilities for current operating leases that are currently recorded off balance sheet. On May 28, 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. ASU 2014-09 supersedes existing revenue recognition guidance, including ASC 605-35 , Revenue Recognition - Construction-Type and Production-Type Contracts . ASU 2014-09 outlines a single set of comprehensive principles for recognizing revenue under GAAP. Among other things, it requires companies to identify contractual performance obligations and determine whether revenue should be recognized at a point in time or over time. These concepts, as well as other aspects of ASU 2014-09, may change the method and/or timing of revenue recognition for certain of our contracts. ASU 2014-09 may be applied either retrospectively or through the use of a modified-retrospective method. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date. The amendments in ASU 2015-14 deferred the effective date of ASU 2014-09 for all entities by one year. Public business entities should apply the guidance in ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. Several related ASUs have been issued since the issuance of ASU 2014-09. These ASUs, which modify certain sections of ASU 2014-09, are intended to promote a more consistent interpretation and application of the principles outlined in the standard. The adoption of ASU 2014-09 will impact our policies, controls, business processes and information systems. To prepare for the changes in this guidance, we developed a plan for adoption. Based on our plan, we commenced an assessment in 2016 on the impacts of this guidance on a representative sample of our existing contract population. The sample contracts selected covered more than 20% of our existing revenue base and included contracts from all of our various contract types. A majority of the contracts we tested were not impacted by the new guidance. For contracts that were impacted, we identified two primary differences. First, the determination of performance obligations under this ASU has led to a different unit of accounting then we are currently applying. Second, we reassessed whether a contract, or performance obligation, met the definition of a "stand ready to perform" or "series" obligation. Those contracts that do not meet the "stand ready to perform" or "series" definition will be transitioned to revenue recognition model where revenue is recognized over time as the performance obligation is satisfied, primarily based on cost incurred. We expect the impact of these changes to produce a more consistent gross margin period-to-period as the obligations are satisfied. We developed and substantially completed a detailed implementation plan during 2017, which includes, among other things, an update to our policies, development of disclosures, updates to our controls and application of the guidance across our contract population. We will adopt ASU 2014-09 under the modified retrospective method to contracts not substantially complete at January 1, 2018. Under the modified retrospective transition method, we will record a transition adjustment to retained earnings. We estimate the cumulative-effect adjustment to retained earnings to be less than $1 million . Based on the results of our detailed implementation plan, we do not expect the adoption of ASU 2014-09 to have a material effect on our consolidated statement of income or our consolidated statement of cash flows. We do expect a more significant impact from the additional disclosures required under the ASU as well as a change in the presentation of contract assets and liabilities on our consolidated balance sheet. Other ASUs effective after December 31, 2017 are not expected to have a material effect on our consolidated financial statements.

Acquisitions (Notes)

Acquisitions (Notes)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisitions [Text Block]	Acquisitions InfoZen LLC (InfoZen) —On October 2, 2017 , we completed the acquisition of InfoZen. The results of InfoZen's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an equity purchase agreement dated September 15, 2017 , by and among InfoZen LLC., IZ Holdings, LLC and other beneficiaries and ManTech Advanced Systems International, Inc. We funded the acquisition with cash on hand and borrowings on our revolving credit facility. InfoZen is a leading IT solution provider, with domain expertise in modernization, agile/DevOps software development, cloud migration and threat monitoring and assessment capabilities in support of critical national and homeland security missions. The purchase agreement did not contain provisions for contingent consideration. For the year ended December 31, 2017, we incurred approximately $0.8 million of acquisition costs related to the InfoZen transaction, which are included in the general and administrative expenses in our consolidated statement of income. The preliminary purchase price of $182.6 million , which includes an estimated working capital adjustment, was preliminarily allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. As we are still in the process of reviewing the fair value of the assets acquired and liabilities assumed and in finalizing the closing working capital adjustment, the purchase price allocation for InfoZen is not complete as of December 31, 2017 . The goodwill recorded related to this transaction will be deductible for tax purposes over 15 years . Recognition of goodwill is largely attributed to the value paid for InfoZen's capabilities to support the DHS and NASA customers and specifically in modernization, agile software development, cloud migration and threat monitoring and assessment capabilities. In preliminarily allocating the purchase price, we considered, among other factors, analysis of historical financial performance and estimates of future performance of InfoZen's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $49.2 million and $5.7 million , respectively. Customer contracts and related relationships represent the underlying relationships and agreements with InfoZen's existing customers. Customer relationships are amortized using the pattern of benefits method over their estimated useful lives of approximately 20 years . Backlog is amortized straight-line over its estimated useful life of 1 year . The weighted-average amortization period for the intangible assets is 18 years . The following table represents the preliminary purchase price allocation for InfoZen (in thousands): Cash and cash equivalents $ 1,406 Receivables 9,434 Prepaid expenses and other 4,245 Goodwill 128,686 Other intangible assets 54,850 Property and equipment 485 Other assets 112 Accounts payable and accrued expenses (8,390 ) Accrued salaries and related expenses (2,893 ) Unearned revenue (4,297 ) Billings in excess of revenue earned (1,018 ) Net assets acquired and liabilities assumed $ 182,620 The following unaudited pro forma financial information below represents our results of operations for years ended December 31, 2017 had the InfoZen acquisition occurred on January 1, 2017 (in thousands). The unaudited proforma financial information below is not intended to represent or be indicative of our actual consolidated results had we completed the acquisition at January 1, 2017. This information should not be taken as representative of our future consolidated results of operations. Revenues and earnings were immaterial for the prior comparative year. Year Ended December 31, 2017 Revenues $ 1,793,752 Net income $ 118,564 Basic earnings per share $ 3.05 Diluted earnings per share $ 3.03 Edaptive Systems LLC (Edaptive) —On December 15, 2016 , we completed the acquisition of Edaptive. The results of Edaptive's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a membership interest purchase agreement dated December 15, 2016 , by and among Edaptive, Everest Holdco, Inc., and certain members of Edaptive and ManTech Advanced Systems International, Inc. Edaptive provides innovative IT solutions primarily to federal health agencies, with a significant focus on the Centers for Medicare & Medicaid Services. The acquisition strategically expands our reach within the federal health community. We funded the acquisition with cash on hand. The membership interest purchase agreement did not contain provisions for contingent consideration. For the year ended December 31, 2016, we incurred approximately $0.3 million of acquisition costs related to the Edaptive transaction, which are included in the general and administrative expenses in our consolidated statement of income. The purchase price of $13.2 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. The goodwill recorded related to this transaction will be deductible for tax purposes over 15 years . Recognition of goodwill is largely attributed to the value paid for Edaptive's capabilities to support Department of Health and Human Services customers and, specifically, in agile software development, testing and automation and business intelligence. In allocating the purchase price, we considered, among other factors, analysis of historical financial performance and estimates of future performance of Edaptive's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $1.1 million and $0.3 million , respectively. Customer contracts and related relationships represent the underlying relationships and agreements with Edaptive's existing customers. Customer relationships are amortized using the pattern of benefits method over their estimated useful lives of approximately 10 years . Backlog is amortized straight-line over its estimated useful life of 1 year . The weighted-average amortization period for the intangible assets is 8 years . The following table represents the purchase price allocation for Edaptive (in thousands): Cash and cash equivalents $ 1,955 Receivables 10,892 Prepaid expenses and other 261 Goodwill 6,193 Other intangible assets 1,689 Property and equipment 502 Other assets 116 Accounts payable and accrued expenses (5,777 ) Accrued salaries and related expenses (2,324 ) Billings in excess of revenue earned (326 ) Net assets acquired and liabilities assumed $ 13,181 We have not disclosed current period, nor pro forma, revenues and earnings attributable to Edaptive as our integration of these operations post-acquisition and the entity's accounting methods pre-acquisition make it impracticable. Oceans Edge, Inc, Cyber Division (OEC) —On June 10, 2016 , we completed the acquisition of certain assets of OEC which constituted a business. The results of OEC's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an asset purchase agreement dated June 10, 2016 , by and among Oceans Edge, Inc., Oceans Edge Cyber, LLC, certain owners of Ocean's Edge, Inc. and ManTech Advanced Systems International, Inc. OEC provides technical and professional services under government contracts in the defense and intelligence industries, including turnkey system solutions in cyber offense and defense, mission operations support and operations assessment and analysis. The OEC team of computer network operations (CNO) professionals will enhance our advanced CNO tools and research and development offerings with new business across the DoD landscape, including United States Cyber Command. The acquisition strategically strengthens our capabilities to support our federal agency customers and, specifically, to engineer and develop new, advanced solutions for wireless devices, networks, and infrastructures. We funded the acquisition with cash on hand. The asset purchase agreement did not contain provisions for contingent consideration. For the year ended December 31, 2016, we incurred approximately $1.2 million of acquisition costs related to the OEC transaction, which are included in the general and administrative expenses in our consolidated statement of income. The purchase price of $47.7 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. The goodwill recorded related to this transaction will be deductible for tax purposes over 15 years . Recognition of goodwill is largely attributed to the value paid for OEC's capabilities in adding additional vulnerability research, development and analysis capabilities to our existing cyber intelligence business. In allocating the purchase price, we considered, among other factors, analysis of historical financial performance and estimates of future performance of OEC's contracts. The components of other intangible assets associated with the acquisition were technology, customer relationships and backlog valued at $3.0 million , $14.0 million and $1.0 million , respectively. Technology represents a suite of mobile analysis and exploitation offerings, which is used by customers in support of their missions. Technology is amortized straight-line over its estimated useful life of 5 years . Customer contracts and related relationships represent the underlying relationships and agreements with OEC's existing customers. Customer relationships are amortized using the pattern of benefits method over their estimated useful lives of approximately 20 years . Backlog is amortized straight-line over its estimated useful life of 1 year . The weighted-average amortization period for the intangible assets is 16 years . The following table represents the purchase price allocation for OEC (in thousands): Receivables $ 138 Goodwill 30,090 Other intangible assets 18,000 Property and equipment 69 Accounts payable and accrued expenses (29 ) Accrued salaries and related expenses (586 ) Net assets acquired and liabilities assumed $ 47,682 We have not disclosed current period, nor pro forma, revenues and earnings attributable to OEC as our integration of these operations post-acquisition and the entity's accounting methods pre-acquisition make it impracticable. Knowledge Consulting Group, Inc. (KCG) —On June 15, 2015 , we completed the acquisition of KCG. The results of KCG's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an agreement and plan of merger dated June 15, 2015 , by and among ManTech Advanced Systems International, Inc., Knight Acquisitions Corporation and KCG. KCG provides comprehensive cyber security services including cloud security, certification and accreditation and various cyber defense solutions across federal and commercial markets. The acquisition strategically positions us to pursue additional cyber work in the Department of Homeland Security, FBI and the intelligence community by leveraging our enhanced cloud security expertise. We funded the acquisition through a combination of cash on hand and borrowings under our revolving credit facility. The agreement did not contain provisions for contingent consideration. For the year ended December 31, 2015, we incurred approximately $0.3 million of acquisition costs related to the KCG transaction, which are included in the general and administrative expenses in our consolidated statement of income. The purchase price of $68.2 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. The goodwill recorded related to this transaction will be deductible for tax purposes over 15 years . Recognition of goodwill is largely attributed to the value paid for KCG's capabilities in providing comprehensive cyber security services throughout the DoD and intelligence community. In allocating the purchase price, we considered, among other factors, analysis of historical financial performance and estimates of future performance of KCG's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $12.4 million and $0.8 million , respectively. Customer contracts and related relationships represent the underlying relationships and agreements with KCG's existing customers. Customer relationships are amortized using the pattern of benefits method over their estimated useful lives of approximately 15 years . Backlog is amortized straight-line over its estimated useful life of 1 year . The weighted-average amortization period for the intangible assets is 14 years . The following table represents the purchase price allocation for KCG (in thousands): Cash and cash equivalents $ 658 Receivables 6,532 Prepaid expenses and other 460 Goodwill 47,487 Other intangible assets 13,219 Property and equipment 1,419 Investments 15 Other assets 31 Accounts payable and accrued expenses (1,269 ) Accrued salaries and related expenses (336 ) Billings in excess of revenue earned (2 ) Net assets acquired and liabilities assumed $ 68,214 We have not disclosed current period, nor pro forma, revenues and earnings attributable to KCG as our integration of these operations post-acquisition and the entity's accounting methods pre-acquisition make it impracticable. Welkin Associates, Ltd. (Welkin) —On April 27, 2015 , we completed the acquisition of Welkin, formerly a wholly-owned subsidiary of Computer Sciences Corporation (CSC). The results of Welkin's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated April 27, 2015 , by and among ManTech International Corporation, CSC and Welkin. Welkin delivers mission-centric services in high-end systems engineering and advanced national security technology and business services. The acquisition strategically positions us to pursue large engineering and support opportunities throughout the intelligence community and DoD. We funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration. For the year ended December 31, 2015, we incurred approximately $0.7 million of acquisition costs related to the Welkin transaction, which are included in the general and administrative expenses in our consolidated statement of income. The purchase price of $34.0 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. The goodwill recorded related to this transaction will be deductible for tax purposes over 15 years . Recognition of goodwill is largely attributed to the value paid for Welkin's capabilities in providing high-end systems engineering and support services throughout the intelligence community and DoD. In allocating the purchase price, we considered, among other factors, analysis of historical financial performance and estimates of future performance of Welkin's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $6.0 million and $0.4 million , respectively. Customer contracts and related relationships represent the underlying relationships and agreements with Welkin's existing customers. Customer relationships are amortized using the pattern of benefits method over their estimated useful lives of approximately 15 years . Backlog is amortized straight-line over its estimated useful life of 1 year . The weighted-average amortization period for the intangible assets is 14 years . The following table represents the purchase price allocation for Welkin (in thousands): Receivables $ 3,901 Prepaid expenses and other 141 Goodwill 24,436 Other intangible assets 6,350 Property and equipment 100 Accounts payable and accrued expenses (436 ) Accrued salaries and related expenses (492 ) Net assets acquired and liabilities assumed $ 34,000 We have not disclosed current period, nor pro forma, revenues and earnings attributable to Welkin as our integration of these operations post-acquisition and the entity's accounting methods pre-acquisition make it impracticable.

Earnings per Share (Notes)

Earnings per Share (Notes)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	Earnings per Share Under ASC 260 , Earnings per Share , the two-class method is an earnings allocation formula that determines earnings per share for each class of common stock according to dividends declared (or accumulated) and participation rights in undistributed earnings. Under that method, basic and diluted earnings per share data are presented for each class of common stock. In applying the two-class method, we determined that undistributed earnings should be allocated equally on a per share basis between Class A and Class B common stock. Under our Certificate of Incorporation, the holders of the common stock are entitled to participate ratably, on a share-for-share basis as if all shares of common stock were of a single class, in such dividends, as may be declared by the Board of Directors. During the years ended December 31, 2017 , 2016 and 2015 , we declared and paid quarterly dividends, each in the amount of $0.21 per share on both classes of common stock. Basic earnings per share has been computed by dividing net income available to common stockholders by the weighted average number of shares of common stock outstanding during each period. Shares issued during the period and shares reacquired during the period are weighted for the portion of the period in which the shares were outstanding. Diluted earnings per share have been computed in a manner consistent with that of basic earnings per share while giving effect to all potentially dilutive common shares that were outstanding during each period. The net income available to common stockholders and weighted average number of common shares outstanding used to compute basic and diluted earnings per share for each class of common stock are as follows (in thousands, except per share amounts): Year Ended 2017 2016 2015 Distributed earnings $ 32,709 $ 32,138 $ 31,543 Undistributed earnings 81,432 24,253 19,584 Net income $ 114,141 $ 56,391 $ 51,127 Class A common stock: Basic net income available to common stockholders $ 75,413 $ 36,885 $ 33,145 Basic weighted average common shares outstanding 25,685 24,944 24,317 Basic earnings per share $ 2.94 $ 1.48 $ 1.36 Diluted net income available to common stockholders $ 75,698 $ 36,988 $ 33,197 Effect of potential exercise of stock options 288 202 109 Diluted weighted average common shares outstanding 25,973 25,146 24,426 Diluted earnings per share $ 2.91 $ 1.47 $ 1.36 Class B common stock: Basic net income available to common stockholders $ 38,728 $ 19,506 $ 17,982 Basic weighted average common shares outstanding 13,190 13,192 13,193 Basic earnings per share $ 2.94 $ 1.48 $ 1.36 Diluted net income available to common stockholders $ 38,443 $ 19,403 $ 17,930 Effect of potential exercise of stock options — — — Diluted weighted average common shares outstanding 13,190 13,192 13,193 Diluted earnings per share $ 2.91 $ 1.47 $ 1.36 For the years ended December 31, 2017 , 2016 and 2015 , options to purchase 265,866 , 369,300 and 1,780,222 shares, respectively, were outstanding but not included in the computation of diluted earnings per share because the options' effect would have been anti-dilutive. For the years ended December 31, 2017 , 2016 and 2015 , there were 463,800 shares, 1,045,789 shares, and 284,320 shares, respectively, issued from the exercise of stock options.

Receivables (Notes)

Receivables (Notes)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Receivables [Text Block]	Receivables We deliver a broad array of IT and technical services solutions under contracts with the U.S. government, state and local governments and commercial customers. The components of contract receivables are as follows (in thousands): December 31, 2017 2016 Billed receivables $ 236,113 $ 247,114 Unbilled receivables: Amounts billable 52,745 52,640 Revenues recorded in excess of funding 12,397 20,078 Retainage 16,312 8,353 Allowance for doubtful accounts (6,157 ) (7,508 ) Receivables-net $ 311,410 $ 320,677 Amounts billable consist principally of amounts to be billed within the next month. Revenues recorded in excess of funding are billable upon receipt of contractual amendments or other modifications. The retainage is billable upon completion of the contract performance and approval of final indirect expense rates by the government. Accounts receivable at December 31, 2017 are expected to be substantially collected within one year except for approximately $1.3 million , of which 97.7% is related to receivables from sales to the U.S. government. The remainder is related to receivables from contracts in which we acted as a subcontractor to other contractors. We do not believe that we have significant exposure to credit risk as accounts receivable and the related unbilled amounts are primarily due from the U.S. government. The allowance for doubtful accounts represents our estimate for exposure to compliance, contractual issues and bad debts related to prime contractors.

Property and Equipment (Notes)

Property and Equipment (Notes)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment [Text Block]	Property and Equipment Major classes of property and equipment are summarized as follows (in thousands): December 31, 2017 2016 Furniture and equipment $ 79,218 $ 51,806 Leasehold improvements 39,022 36,439 Property and equipment-gross 118,240 88,245 Accumulated depreciation and amortization (72,158 ) (65,124 ) Property and equipment-net $ 46,082 $ 23,121 Depreciation and amortization expense related to property and equipment for the years ended December 31, 2017 , 2016 and 2015 was $9.5 million , $7.8 million and $8.5 million , respectively.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets (Notes)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets [Text Block]	Goodwill and Other Intangible Assets Under ASC 350 , Intangibles - Goodwill and Other , goodwill is to be reviewed at least annually for impairment and whenever events or circumstances indicate that the carrying value of goodwill may not be fully recoverable. We have elected to perform this annual review as of October 31st of each calendar year. In reviewing goodwill for impairment, we have the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the estimated fair value of a reporting unit is less than its carrying amount. If we elect to perform a qualitative assessment and determine that an impairment is more likely than not, the entity is then required to perform the existing two-step quantitative impairment test (described below), otherwise no further analysis is required. We also may elect not to perform the qualitative assessment and, instead, proceed directly to the two-step quantitative impairment test. The goodwill impairment test is a two-step process performed at the reporting unit level. The first step of the goodwill impairment test compares the fair value of a reporting unit with its carrying amount (including goodwill). If the reporting unit's fair value exceeds its carrying value, no further procedures are required. However, if the reporting unit's fair value is less than its carrying value, an impairment of goodwill may exist, requiring a second step to be performed. Step two of this test measures the amount of the impairment loss, if any. Step two of this test requires the allocation of the reporting unit's fair value to its assets and liabilities, including any unrecognized intangible assets in a hypothetical analysis that calculates the implied fair value of goodwill as if the reporting unit were being acquired in a business combination. If the implied fair value of goodwill is less than the carrying value, the difference is recorded as a goodwill impairment charge in operations. The fair values of the reporting units are determined based on a weighting of the income approach, market approach and market transaction approach. The income approach is a valuation technique in which fair value is based from forecasted future cash flow discounted at the appropriate rate of return commensurate with the risk as well as current rates of return for equity and debt capital as of the valuation date. The forecast used in our estimation of fair value was developed by management based on a contract basis, incorporating adjustments to reflect known contract and market considerations (such as reductions and uncertainty in government spending, pricing pressure and opportunities). The discount rate utilizes a risk adjusted weighted average cost of capital. The market approach is a valuation technique in which the fair value is calculated based on market prices realized in an actual arm's length transaction. The technique consists of undertaking a detailed market analysis of publicly traded companies that provides a reasonable basis for comparison to us. Valuation ratios, which relate market prices to selected financial statistics derived from comparable companies, are selected and applied to us after consideration of adjustments for financial position, growth, market, profitability and other factors. The market transaction approach is a valuation technique in which the fair value is calculated based on market prices realized in actual arm's length transactions. The technique consists of undertaking a detailed market analysis of merged and acquired companies that provides a reasonable basis for comparison to us. Valuation ratios, which relate market prices to selected financial statistics derived from comparable companies, are selected and applied to us after consideration of adjustments for financial position, growth, market, profitability and other factors. To assess the reasonableness of the calculated reporting unit fair values, we compare the sum of the reporting units' fair values to our market capitalization (per share stock price times the number of shares outstanding) and calculate an implied control premium (the excess of the sum of the reporting units' fair values over the market capitalization) and then assess the reasonableness of our implied control premium. The changes in the carrying amounts of goodwill during fiscal years 2017 and 2016 were as follows (in thousands): Goodwill Balance Goodwill at December 31, 2015 $ 919,591 Acquisitions 36,283 Goodwill at December 31, 2016 955,874 Acquisitions 128,686 Goodwill at December 31, 2017 $ 1,084,560 Other intangible assets consisted of the following (in thousands): December 31, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Other intangible assets: Contract and program intangible assets $ 355,932 $ 179,049 $ 176,883 $ 301,082 $ 158,671 $ 142,411 Capitalized software cost for internal use 46,937 29,472 17,465 39,332 26,815 12,517 Other 58 58 — 58 55 3 Total other intangible assets-net $ 402,927 $ 208,579 $ 194,348 $ 340,472 $ 185,541 $ 154,931 Amortization expense relating to intangible assets for the years ended December 31, 2017 , 2016 and 2015 was $23.5 million , $21.8 million and $21.2 million , respectively. We estimate that we will have the following amortization expense for the future periods indicated below (in thousands): Year ending: December 31, 2018 $ 25,472 December 31, 2019 $ 21,013 December 31, 2020 $ 20,172 December 31, 2021 $ 17,443 December 31, 2022 $ 14,843

Debt (Notes)

Debt (Notes)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt [Text Block]	Debt Revolving Credit Facility -We maintain a credit agreement with a syndicate of lenders led by Bank of America, N.A., as sole administrative agent. The credit agreement provides for a $500 million revolving credit facility, with a $75 million letter of credit sublimit and a $30 million swing line loan sublimit. The credit agreement also includes an accordion feature that permits us to arrange with the lenders for the provision of additional commitments. The maturity date is August 17, 2022 . On August 17, 2017 , we amended the credit agreement, which among other things increased the letter of credit sublimit to $75 million . We deferred $2.2 million in debt issuance costs, cumulatively over the agreement, which are amortized over the term of the credit agreement. Borrowings under our credit agreement are collateralized by substantially all of our assets and our Material Subsidiaries (as defined in the credit agreement) and bear interest at one of the following variable rates as selected by us at the time of borrowing: a LIBOR based rate plus market spreads ( 1.25% to 2.25% based on our consolidated total leverage ratio) or Bank of America's base rate plus market spreads ( 0.25% to 1.25% based on our consolidated total leverage ratio). The aggregate annual weighted average interest rates were 2.99% and 3.75% for the years ended December 31, 2017 and 2016 , respectively. The terms of the credit agreement permit prepayment and termination of the loan commitments at any time, subject to certain conditions. The credit agreement requires us to comply with specified financial covenants, including the maintenance of certain leverage ratios and a certain consolidated coverage ratio. The credit agreement also contains various covenants, including 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 our ability to incur liens, incur additional indebtedness, make investments, make acquisitions and undertake certain other actions. As of, and during the fiscal years ending, December 31, 2017 and 2016 , we were in compliance with our financial covenants under the credit agreement. There was $31.0 million and $0 outstanding on our revolving credit facility at December 31, 2017 and 2016 , respectively. The weighted average borrowings under the revolving portion of the facility during the years ended December 31, 2017 and 2016 were $2.7 million and $0 , respectively. The maximum available borrowing under the revolving credit facility at December 31, 2017 was $453.7 million . At December 31, 2017 and 2016 , we were contingently liable under letters of credit totaling $15.3 million and $23.1 million , respectively, which reduces our availability to borrow under our revolving credit facility.

Commitments and Contingencies (

Commitments and Contingencies (Notes)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	Commitments and Contingencies Contracts with the U.S. government, including subcontracts, are subject to extensive legal and regulatory requirements and, from time-to-time, agencies of the U.S. government, in the ordinary course of business, investigate whether our operations are conducted in accordance with these requirements and the terms of the relevant contracts. U.S. government investigations of us, whether related to our U.S. government contracts or conducted for other reasons, could result in administrative, civil, or criminal liabilities, including repayments, fines or penalties being imposed upon us, or could lead to suspension or debarment from future U.S. government contracting activities. Management believes it has adequately reserved for any losses that may be experienced from any investigation of which it is aware. The Defense Contract Audit Agency has substantially completed our incurred cost audits through 2012 with no material adjustments. The remaining audits for 2013 through 2016 are not expected to have a material effect on our financial position, results of operations or cash flow and management believes it has adequately reserved for any losses. In the normal course of business, we are involved in certain governmental and legal proceedings, claims and disputes and have litigation pending under several suits. We believe that the ultimate resolution of these matters will not have a material effect on our financial position, results of operations or cash flows, except for the matter noted below. We are a defendant in a lawsuit filed by two former employees alleging retaliation under both the False Claims Act (FCA) and the Defense Contractor Whistleblower Protection Act (DCWPA). In November 2016, we went to trial and the jury returned a verdict in favor of both plaintiffs, finding us liable for retaliation under both the FCA and the DCWPA, and awarded $0.8 million in compensatory damages for emotional distress. As a result of the jury's verdict, these plaintiffs are also entitled to awards of (i) back pay, (ii) front pay and (iii) attorneys' fees and costs. We challenged the jury’s verdict at the trial court level - both in terms of liability and in terms of the amount of the compensatory damages awarded. Specifically, we have asked the trial judge to: (i) grant us judgment as a matter of law and dismiss the retaliation claims under both the FCA and the DCWPA, and (ii) vacate the jury’s awards of compensatory damages. On May 19, 2017, the court, by a Memorandum Opinion and Order, vacated the jury's verdict with respect to the awards of $0.8 million in compensatory damages for emotional distress and awarded damages in the total amount of $1.8 million for back pay and front pay. On August 30, 2017, the judge awarded attorneys' fees and costs and the judgment entered on May 19, 2017 in favor of both plaintiffs was amended as follows: (i) to plaintiff #1, $0.3 million in attorneys' fees and costs; $0.9 million in back pay with interest at the rate of $16.92 per diem from November 18, 2016 through the date of the amended judgment, and $0.3 million in front pay; and (ii) to plaintiff #2, $0.3 million in attorneys’ fees and costs; $0.5 million in back pay with interest at the rate of $9.79 per diem from November 18, 2016 through the date of the amended judgment, and $0.2 million in front pay. We have filed an appeal in the Fourth Circuit Court of Appeals. As of December 31, 2017 , we accrued a liability for $2.3 million and recorded a receivable for $2.8 million . Through the appeals process, our liability could be further reduced or, if the plaintiffs are successful, increased an additional $0.8 million . We have an insurance policy that covers the amount of the liability, therefore, no loss was recognized as of the year ended December 31, 2017 . The impact of future events in connection with this matter are not expected to have a material effect on our financial position, results of operations or cash flow. We have $15.3 million outstanding on our letter of credit, of which $15.2 million is related to an outstanding performance bond in connection with a contract between ManTech MENA, LLC and Jadwalean International Operations and Management Company to fulfill technical support requirements for the Royal Saudi Air Force. We lease office space and equipment under long-term operating leases. A number of the leases contain renewal options and escalation clauses. Office space and equipment rent expense totaled approximately $36.9 million , $37.4 million and $37.2 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. We had $10.6 million and $11.1 million of deferred rent liabilities resulting from recording rent expense on a straight-line basis over the life of the respective lease for the years ended December 31, 2017 and 2016 , respectively. At December 31, 2017 , aggregate future minimum rental commitments under these leases are as follows (in thousands): Total Year ending: December 31, 2018 $ 32,353 December 31, 2019 29,252 December 31, 2020 23,048 December 31, 2021 19,964 December 31, 2022 16,793 Thereafter 18,692 Total $ 140,102

Stockholders Equity and Stock-B

Stockholders Equity and Stock-Based Compensation (Notes)	12 Months Ended
	Dec. 31, 2017
Stockholders Equity and Stock-Based Compensation [Abstract]
Stockholders Equity and Stock-Based Compensation [Text Block]	Stockholders' Equity and Stock-Based Compensation Common Stock -We have 150,000,000 shares of authorized Class A common stock, par value $0.01 per share. We have 50,000,000 shares of authorized Class B common stock, par value $0.01 per share. On December 31, 2017 , there were 26,041,660 shares of Class A common stock outstanding, 244,113 shares of Class A common stock recorded as treasury stock and 13,189,245 shares of Class B common stock outstanding. Holders of Class A common stock are entitled to one vote for each share held of record and holders of Class B common stock are entitled to ten votes for each share held of record, except with respect to any “going private transaction” (generally, a transaction in which George J. Pedersen (our Executive Chairman and Chairman of the Board), his affiliates, his direct and indirect permitted transferees or a group, generally including Mr. Pedersen, such affiliates and permitted transferees, seek to buy all outstanding shares), as to which each share of Class A common stock and Class B common stock are entitled to one vote per share. The Class A common stock and the Class B common stock vote together as a single class on all matters submitted to a vote of stockholders, including the election of directors, except as required by law. Holders of common stock do not have cumulative voting rights in the election of directors. Stockholders are entitled to receive, when and if declared by the Board of Directors from time-to-time, such dividends and other distributions in cash, stock or property from our assets or funds legally and contractually available for such purposes subject to any dividend preferences that may be attributable to preferred stock that may be authorized. Each share of Class A common stock and Class B common stock is equal in respect to dividends and other distributions in cash, stock or property, except that in the case of stock dividends, only shares of Class A common stock will be distributed with respect to the Class A common stock and only shares of Class B common stock will be distributed with respect to Class B common stock. In no event will either Class A common stock or Class B common stock be split, divided or combined unless the other class is proportionately split, divided or combined. The shares of Class A common stock are not convertible into any other series or class of securities. Each share of Class B common stock, however, is freely convertible into one share of Class A common stock at the option of the Class B stockholder. Upon the death of Mr. Pedersen, all outstanding shares of Class B common stock automatically convert to Class A common stock. Preferred Stock -We are authorized to issue an aggregate of 20,000,000 shares of preferred stock, $0.01 par value per share, the terms and conditions of which are determined by our Board of Directors upon issuance. The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of holders of any shares of preferred stock that we may designate and issue in the future. At December 31, 2017 and 2016 , no shares of preferred stock were outstanding and the Board of Directors currently has no plans to issue a series of preferred stock. Accounting for Stock-Based Compensation: Our 2016 Management Incentive Plan (the Plan) was designed to attract, retain and motivate key employees. The types of awards available under the Plan include stock options, restricted stock and RSUs. Equity awards granted under the Plan are settled in shares of Class A common stock. At the beginning of each year, the Plan provides that the number of shares available for issuance automatically increases by an amount equal to 1.5% of the total number of shares of Class A and Class B common stock outstanding on December 31st of the previous year. On January 2, 2018 , there were 588,464 additional shares made available for issuance under the Plan. Through December 31, 2017 , the Board of Directors has authorized the issuance of up to 13,963,435 shares under this Plan. Through December 31, 2017 , the remaining aggregate number of shares of our common stock available for future grants under the Plan was 5,980,594 . The Plan expires in March 2026 . The Plan is administered by the compensation committee of our Board of Directors, along with its delegates. Subject to the express provisions of the Plan, the committee has the Board of Directors' authority to administer and interpret the Plan, including the discretion to determine the exercise price, vesting schedule, contractual life and the number of shares to be issued. Stock Compensation Expense -For the years ended December 31, 2017 , 2016 and 2015 , we recorded $6.3 million , $3.3 million and $4.4 million of stock-based compensation expense, respectively. No compensation expense of employees with stock awards, including stock-based compensation expense, was capitalized during the periods. For the year ended December 31, 2017 , we recorded $2.7 million to income tax expense for tax benefits related to the exercise of stock options, vested cancellations and the vesting of restricted stock. For the year ended December 31, 2016 and 2015 , we recorded $0.1 million and $3.0 million , respectively, to paid in capital related to tax deficiencies from the exercise of stock options, vested cancellations and the vesting of restricted stock. Stock Options- Under the Plan, we have issued stock options. A stock option granted gives the holder the right, but not the obligation to purchase a certain number of shares at a predetermined price for a specific period of time. We typically issue options that vest over three years in equal installments beginning on the first anniversary of the date of grant. Under the terms of the Plan, the contractual life of the option grants may not exceed eight years . During the years ended December 31, 2017 , 2016 and 2015 , we issued options that expire five years from the date of grant. Fair Value Determination -We have used the Black-Scholes-Merton option pricing model to determine fair value of our stock option awards on the date of grant. We will reconsider the use of the Black-Scholes-Merton model if additional information becomes available in the future that indicates another model would be more appropriate or if grants issued in future periods have characteristics that cannot be reasonably estimated under this model. The following weighted-average assumptions were used for option grants during the years ended December 31, 2017 , 2016 and 2015 : • Volatility -The expected volatility of the options granted was estimated based upon historical volatility of our share price through weekly observations of our trading history. • Expected life of options -The expected life of options granted to employees was determined from historical exercises of the grantee population. The options had graded vesting over three years in equal installments beginning on the first anniversary of the date of the grant and a contractual term of five years . • Risk-free interest rate -The yield on zero-coupon U.S. Treasury strips was used to extrapolate a forward-yield curve. This “term structure” of future interest rates was then input into a numeric model to provide the equivalent risk-free rate to be used in the Black-Scholes-Merton model based on the expected term of the underlying grants. • Dividend yield -The Black-Scholes-Merton valuation model requires an expected dividend yield as an input. We have calculated our expected dividend yield based on an expected annual cash dividend of $0.84 per share. The following table summarizes weighted-average assumptions used in our calculations of fair value for the years ended December 31, 2017 , 2016 and 2015 : Year Ended 2017 2016 2015 Volatility 25.59 % 23.70 % 26.16 % Expected life of options 3 years 3 years 3 years Risk-free interest rate 1.72 % 1.10 % 1.15 % Dividend yield 2.75 % 2.88 % 3.00 % Stock Option Activity -The weighted-average fair value of options granted during the years ended December 31, 2017 , 2016 and 2015 , as determined under the Black-Scholes-Merton valuation model, was $6.75 , $4.60 and $4.59 , respectively. Option grants that vested during the years ended December 31, 2017 , 2016 and 2015 had a combined fair value of $1.7 million , $2.6 million and $3.6 million , respectively. The following table summarizes stock option activity for the years ended December 31, 2017 , 2016 and 2015 : Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2014 3,391,032 $ 32.76 $ 4,722 Granted 237,853 $ 30.87 Exercised (284,320 ) $ 27.51 $ 1,348 Cancelled and expired (849,255 ) $ 39.56 Stock options outstanding at December 31, 2015 2,495,310 $ 30.86 $ 3,583 Granted 199,938 $ 34.22 Exercised (1,045,789 ) $ 29.24 $ 8,858 Cancelled and expired (489,040 ) $ 37.91 Stock options outstanding at December 31, 2016 1,160,419 $ 29.93 $ 14,299 Granted 534,030 $ 42.90 Exercised (463,800 ) $ 29.34 $ 7,203 Cancelled and expired (61,241 ) $ 33.80 Stock options outstanding at December 31, 2017 1,169,408 $ 35.88 $ 16,731 3 years Stock options exercisable at December 31, 2017 484,429 $ 29.22 $ 10,156 2 years The following table summarizes non-vested stock options for the year ended December 31, 2017 : Number of Shares Weighted Average Fair Value Non-vested stock options at December 31, 2016 562,927 $ 4.66 Granted 534,030 $ 6.75 Vested (367,729 ) $ 4.71 Cancelled (44,249 ) $ 5.11 Non-vested stock options at December 31, 2017 684,979 $ 6.23 Unrecognized compensation expense related to outstanding stock options was $3.6 million as of December 31, 2017 , which is expected to be recognized over a weighted-average period of 3 years and will be adjusted for forfeitures as they occur. Restricted Stock -Under the Plan, we have issued restricted stock. A restricted stock award is an issuance of shares that cannot be sold or transferred by the recipient until the vesting period lapses. Restricted stock issued to members of our Board of Directors vest in one year . The related compensation expense is recognized over the service period and is based on the grant date fair value of the stock and the number of shares expected to vest. The grant date fair value of the restricted stock is equal to the closing market price of our common stock on the date of grant. Restricted Stock Activity -The following table summarizes the restricted stock activity during the years ended December 31, 2017 and 2016 : Number of Shares Weighted Average Fair Value Non-vested restricted stock at December 31, 2015 21,000 $ 28.98 Granted 18,000 $ 33.84 Vested (21,000 ) $ 28.98 Non-vested restricted stock at December 31, 2016 18,000 $ 33.84 Granted 24,000 $ 37.90 Vested (18,000 ) $ 33.84 Non-vested restricted stock at December 31, 2017 24,000 $ 37.90 RSUs- Under the Plan, we issued RSUs. RSUs are not actual shares, but rather a right to receive shares in the future. The shares are not issued and the employee cannot sell or transfer shares prior to vesting and has no voting rights until the RSUs vest. Employees who are granted RSUs do not receive dividend payments during the vesting period. The employees' RSUs will result in the delivery of shares if (a) performance criteria is met and (b) the employee remains employed, in good standing, through the date of the performance period or death. The performance period is 2 years . During the year ended December 31, 2016, we granted 26,788 time-based RSUs to an officer which did not contain additional performance criteria (half will vest four years after the date of grant and the other half will vest five years after the date of grant). The grant date fair value of the RSUs is equal to the closing market price of our common stock on the grant date less the present value of dividends expected to be awarded during the service period. We recognize the grant date fair value of RSUs of shares we expect to issue as compensation expense ratably over the requisite service period. RSU Activity- The following table summarizes the RSU activity during the years ended December 31, 2017 and 2016 : Number of Units Weighted Average Fair Value RSUs at December 31, 2015 93,450 $ 30.84 Granted 132,988 $ 29.50 Forfeited (20,100 ) $ 29.56 RSUs at December 31, 2016 206,338 $ 30.10 Granted 55,830 $ 35.34 Vested (3,300 ) $ 30.60 Forfeited (97,525 ) $ 31.00 RSUs at December 31, 2017 161,343 $ 31.36

Retirement Plans (Notes)

Retirement Plans (Notes)	12 Months Ended
	Dec. 31, 2017
Retirement Benefits [Abstract]
Retirement Plans [Text Block]	Retirement Plans As of December 31, 2017 , we maintained a qualified defined contribution plan. Our qualified defined contribution plan covers substantially all employees and complies with Section 401 of the Internal Revenue Code. Under this plan, we stipulated a basic matching contribution that matches a portion of the participants' contribution based upon a defined schedule. Additionally, this plan contains a discretionary contribution component where we may contribute additional amounts based on a percentage of eligible employees' compensation. Contributions are invested by an independent investment company. The choice of investment alternatives is at the election of each participating employee. Our contributions to the plan were approximately $20.6 million , $19.8 million and $18.5 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. As of December 31, 2017 , we also maintained an Employee Supplemental Savings Plan (ESSP), which is a nonqualified deferred compensation plan for certain key employees. Under this plan, eligible employees may defer up to 75% of qualified annual base compensation and 100% of bonus. In the ESSP, participant deferral accounts are credited with a rate of return based on investment elections as selected by the participant. The assets related to the ESSP are held in a rabbi trust owned by us for benefit of the participating employees. The trust investments are in the form of variable universal life insurance products, which are owned by us. These investments seek to replicate the return of the participant investment elections. Employee contributions to this plan were approximately $3.0 million , $2.6 million and $2.8 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. We maintained a nonqualified supplemental defined benefit pension plan for certain retired employees of an acquired company as of December 31, 2017 . These plans were informally and partially funded beginning in 1999 through a rabbi trust. Assets held in a rabbi trust are not eligible to be included in the calculation of plan status. At both December 31, 2017 and 2016 , 100% of the rabbi trust assets were invested in a money market account with a commercial bank. All covered employees retired prior to 1998. Our benefit obligation was $1.2 million and $1.1 million at December 31, 2017 and 2016 , respectively.

Income Taxes (Notes)

Income Taxes (Notes)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes [Text Block]	Income Taxes The domestic and foreign components of income operations before income taxes and equity method investments were as follows (in thousands): Year Ended 2017 2016 2015 Domestic $ 97,718 $ 89,988 $ 85,665 Foreign (476 ) 82 (311 ) Income from operations before income taxes and equity method investments $ 97,242 $ 90,070 $ 85,354 The provision for income taxes was comprised of the following components (in thousands): Year Ended 2017 2016 2015 Current provision: Federal $ 5,340 $ 13,454 $ 2,714 State 2,523 2,394 1,247 Foreign 38 (45 ) 77 7,901 15,803 4,038 Deferred (benefit) provision: Federal (28,013 ) 17,170 27,817 State 3,313 2,831 5,825 (24,700 ) 20,001 33,642 Non-current (benefit) resulting from allocating tax benefits directly to additional paid in capital and changes in liabilities: Federal (60 ) (1,573 ) (2,568 ) State — (445 ) (746 ) (60 ) (2,018 ) (3,314 ) (Benefit) provision for income taxes $ (16,859 ) $ 33,786 $ 34,366 For the years ended December 31, 2017, 2016 and 2015 the non-current benefits related to liabilities for uncertain tax positions was $0.1 million , $0.2 million and $0.3 million , respectively. The schedule of effective income tax rate reconciliation is as follows: Year Ended 2017 2016 2015 Statutory U.S. Federal tax rate 35.0 % 35.0 % 35.0 % Increase (decrease) in tax rate resulting from: Net deferred tax liability remeasurement (52.0 )% — % — % State taxes—net of Federal benefit 3.9 % 3.4 % 4.8 % Stock-based compensation (2.8 )% — % — % ESSP (1.5 )% (0.7 )% 0.2 % Excess executive compensation 0.4 % 0.7 % 0.5 % Section 199 deductions (0.4 )% (0.4 )% (0.4 )% Other, net 0.1 % (0.5 )% 0.1 % Effective tax rate (17.3 )% 37.5 % 40.2 % We paid income taxes, net of refunds, of $15.9 million , $18.1 million and $6.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. Deferred income taxes arise from temporary differences between the tax basis of assets and liabilities and their reported amounts in the financial statements. A summary of the tax effect of the significant components of deferred income taxes is as follows (in thousands): December 31, 2017 2016 Gross deferred tax liabilities: Goodwill and other assets $ 100,967 $ 131,367 Unbilled receivables 11,693 18,608 Property and equipment 7,303 2,657 Total 119,963 152,632 Gross deferred tax assets: Retirement and other liabilities (20,636 ) (27,258 ) Allowance for potential contract losses and other contract reserves (1,598 ) (3,005 ) Federal and state operating loss carryforwards (1,252 ) (560 ) Less: Valuation allowance 717 272 Total (22,769 ) (30,551 ) Net deferred tax liabilities $ 97,194 $ 122,081 In connection with our initial analysis of the impact of the Tax Cuts and Jobs Act, our income tax expense was reduced by $50.6 million for the year ended December 31, 2017 from a re-measurement of our existing deferred tax assets and liabilities. We have not completed our accounting for the income tax effects of certain elements of the Tax Cuts and Jobs Act, specifically related to the future deductibility of certain executive compensation expenses, acquisition accounting for InfoZen, and a detailed review of capitalized assets that qualify for immediate deduction. We have recorded provisional adjustments for these matters for the year ended December 31, 2017 . At December 31, 2017 , we had state and foreign net operating losses of approximately $9.9 million and $3.5 million , respectively. The state net operating losses expire beginning 2019 through 2035 . We recorded a valuation allowance against the foreign net operating losses as we do not believe the loss will be fully utilized in the future. A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in thousands): December 31, 2017 2016 2015 Gross unrecognized tax benefits at beginning of year $ 293 $ 519 $ 785 Lapse in statute of limitations (105 ) (285 ) (266 ) Increases in tax positions for current year 32 59 — Gross unrecognized tax benefits at end of year $ 220 $ 293 $ 519 The total liability for gross unrecognized tax benefits as of December 31, 2017 , 2016 and 2015 includes $0.2 million , $0.2 million and $0.4 million , respectively, of unrecognized net tax benefits which, if ultimately recognized, would reduce our annual effective tax rate in a future period. We are subject to income taxes in the U.S., various state and foreign jurisdictions. Tax statutes and regulations within each jurisdiction are subject to interpretation and require significant judgment to apply. We are no longer subject to U.S. federal or non-U.S. income tax examinations by tax authorities for the years before 2013. We are no longer subject to U.S. state tax examinations by tax authorities for the years before 2012. We believe it is reasonably possible that $0.1 million of gross unrecognized tax benefits will be settled within the next year due to expirations of statute of limitations.

Business Segment and Geographic

Business Segment and Geographic Area Information (Notes)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Business Segment And Geographic Area Information [Text Block]	Business Segment and Geographic Area Information We have one reportable segment. We deliver a broad array of IT and technical services solutions under contracts with the U.S. government. Our U.S. government customers typically exercise independent contracting authority, and even offices or divisions within an agency or department may directly, or through a prime contractor, use our services as a separate customer so long as that customer has independent decision-making and contracting authority within its organization. Revenues from the U.S. government under prime contracts and subcontracts were approximately 98% , 98% and 99% of our total revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. We treat sales to U.S. government customers as sales within the U.S. regardless of where the services are performed. U.S. revenues were approximately 98% , 98% and 100% of our total revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. International revenues were approximately 2% , 2% and 0% of our total revenues for the years ended December 31, 2017 , 2016 and 2015 , respectively. Furthermore, substantially all assets from continuing operations were held in the U.S. for the years ended December 31, 2017 , 2016 and 2015 .

Divestiture of ManTech Cyber So

Divestiture of ManTech Cyber Solutions International and Investment (MCSI) in CounterTack Inc. (CounterTack) (Notes)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Divestiture of ManTech Cyber Solutions International and Investment in CounterTack Inc. [Text Block]	Divestiture of ManTech Cyber Solutions International (MCSI) and Investment in CounterTack Inc. (CounterTack) On July 13, 2015, we divested MCSI, which was engaged in the business of providing commercial cyber products. We received consideration of preferred stock in CounterTack that has a fair value of $6.7 million . The fair value is based on the quoted price for the identical item held by another party (Level 3). We recorded a gain on the sale of $1.7 million , which is included in the other income (expense), net line item on the consolidated statement of income for the year ended December 31, 2015. We recorded transaction costs associated with the divestiture of $1.2 million . The divestiture did not qualify to be presented as discontinued operations as it did not represent a strategic shift that would have a major effect on our operations and financial results. On July 13, 2015, we purchased additional preferred stock in CounterTack for $3.8 million . We account for our investment in CounterTack preferred stock under the cost method of accounting for investments.

Quarterly Financial Information

Quarterly Financial Information (Unaudited) (Notes)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited) [Text Block]	Quarterly Financial Information (Unaudited) The quarterly financial data reflects, in our opinion, all normal and recurring adjustments to present fairly the results of operations for such periods. Results of any one or more quarters are not necessarily indicative of annual results or continuing trends. The following tables set forth selected unaudited quarterly financial data: 2017 March 31, June 30, September 30, December 31, (in thousands, except per share data) Revenues $ 418,374 $ 413,694 $ 422,665 $ 462,285 Operating income $ 24,390 $ 24,935 $ 23,140 $ 25,729 Income from operations before income taxes and equity method investments $ 24,159 $ 24,651 $ 23,114 $ 25,318 Net income $ 15,028 $ 15,561 $ 15,182 $ 68,370 Class A common stock: Basic weighted average common shares outstanding 25,547 25,618 25,684 25,886 Basic earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.75 Diluted weighted average common shares outstanding 25,778 25,827 25,929 26,353 Diluted earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.73 Class B common stock: Basic weighted average common shares outstanding 13,191 13,191 13,191 13,189 Basic earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.75 Diluted weighted average common shares outstanding 13,191 13,191 13,191 13,189 Diluted earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.73 2016 March 31, June 30, September 30, December 31, (in thousands, except per share data) Revenues $ 390,662 $ 401,354 $ 415,402 $ 394,178 Operating income $ 21,945 $ 24,214 $ 23,500 $ 21,304 Income from operations before income taxes and equity method investments $ 21,708 $ 23,972 $ 23,365 $ 21,025 Net income $ 13,216 $ 14,782 $ 14,664 $ 13,729 Class A common stock: Basic weighted average common shares outstanding 24,476 24,707 25,164 25,423 Basic earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.36 Diluted weighted average common shares outstanding 24,567 24,916 25,429 25,667 Diluted earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.35 Class B common stock: Basic weighted average common shares outstanding 13,192 13,192 13,192 13,191 Basic earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.36 Diluted weighted average common shares outstanding 13,192 13,192 13,192 13,191 Diluted earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.35

Schedule II

Schedule II	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	SCHEDULE II Valuation and Qualifying Accounts Activities in our allowance accounts for the years ended December 31, 2017 , 2016 and 2015 were as follows (in thousands): Doubtful Accounts Balance at Beginning of Period Charged to Costs and Expenses Deductions Other* Balance at End of Period 2015 $ 9,830 — (552 ) (805 ) $ 8,473 2016 $ 8,473 — (215 ) (750 ) $ 7,508 2017 $ 7,508 — — (1,351 ) $ 6,157 * Other represents doubtful account reserves released or recorded as part of net revenues for estimated customer disallowances. Deferred Tax Asset Valuation Balance at Beginning of Period Charged to Costs and Expenses Deductions Other Balance at End of Period 2015 $ 64 — — (64 ) $ — 2016 $ — 272 — — $ 272 2017 $ 272 444 — 1 $ 717

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles of Consolidation [Policy Text Block]	Principles of Consolidation -Our consolidated financial statements include the accounts of ManTech International Corporation, subsidiaries we control and variable interest entities that are required to be consolidated. All intercompany accounts and transactions have been eliminated.
Use of Accounting Estimates [Policy Text Block]	Use of Accounting Estimates -We prepare our consolidated financial statements in conformity with U.S. GAAP, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates involve judgments with respect to, among other things, various future economic factors that are difficult to predict and are beyond the control of us. Therefore, actual amounts could differ from these estimates.
Revenue Recognition [Policy Text Block]	Revenue Recognition -We derive the majority of our revenues from cost-plus-fixed-fee, cost-plus-award-fee, fixed-price and time-and-materials contracts. Revenues for cost-reimbursable contracts are recorded as reimbursable costs are incurred, including an estimated share of the applicable contractual fees earned. For performance-based fees under cost-reimbursable contracts, we recognize the relevant portion of the expected fee to be awarded by the customer at the time such fee can be reasonably estimated, based on factors such as our prior award experience and communications with the customer regarding performance, or upon approval by the customer. For time-and-materials contracts, revenues are recognized to the extent of billable rates times hours delivered plus materials and other reimbursable costs incurred. For long-term fixed-price contracts, revenues are recognized at a rate per unit as the units are delivered or by other methods to measure services provided. Revenues from other long-term fixed-price contracts are recognized ratably over the contract period or by other appropriate methods to measure services provided. Contract costs are expensed as incurred except for certain limited long-term contracts noted below. For long-term contracts, specifically described in the scope section of ASC 605-35 , Revenue Recognition - Construction-Type and Production-Type Contracts , we apply the percentage of completion method. Under the percentage of completion method, income is recognized at a consistent profit margin over the period of performance based on estimated profit margins at completion of the contract. This method of accounting requires estimating the total revenues and total contract cost at completion of the contract. During the performance of long-term contracts, these estimates are periodically reviewed and revisions are made as required using the cumulative catch-up method of accounting. The impact on revenues and contract profit as a result of these revisions is included in the periods in which the revisions are made. This method can result in the deferral of costs or the deferral of profit on these contracts. Because we assume the risk of performing a fixed-price contract at a set price, the failure to accurately estimate ultimate costs or to control costs during performance of the work could result, and in some instances has resulted, in reduced profits or losses for such contracts. Estimated losses on contracts at completion are recognized when identified. In certain circumstances, revenues are recognized when contract amendments have not been finalized.
Cost of Services [Policy Text Block]	Cost of Services -Cost of services consists primarily of compensation expenses for program personnel, the fringe benefits associated with this compensation and other direct expenses incurred to complete programs, including cost of materials and subcontractor efforts.
General and Administrative Expenses [Policy Text Block]	General and Administrative Expenses- General and administrative expenses include the salaries and wages, plus associated fringe benefits of our employees not performing work directly for customers, and associated facilities costs. Among the functions covered by these costs are corporate business development, bid and proposal, contracts administration, finance and accounting, legal, corporate governance and executive and senior management. In addition, we include stock-based compensation, as well as depreciation and amortization expenses related to the general and administrative function. We recognize interest related to unrecognized tax benefits within interest expense and penalties related to unrecognized tax benefits in general and administrative expenses. We classify indirect costs incurred as cost of services and general and administrative expenses in the same manner as such costs are defined in our disclosure statements under U.S. Government Cost Accounting Standards.
Cash and Cash Equivalents [Policy Text Block]	Cash and Cash Equivalents -For the purpose of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks and short-term investments with maturity dates of three months or less at the date of purchase.
Property and Equipment [Policy Text Block]	Property and Equipment -Property and equipment are recorded at original cost to us. Upon sale or retirement, the costs and related accumulated depreciation or amortization are eliminated from the respective accounts and any resulting gain or loss is included in income. Maintenance and repairs are charged to expense as incurred.
Depreciation and Amortization Method [Policy Text Block]	Depreciation and Amortization Method -Furniture and office equipment are depreciated using the straight-line method with estimated useful lives ranging from one to seven years . Leasehold improvements are amortized using the straight-line method over the shorter of the asset's useful life or the term of the lease.
Goodwill [Policy Text Block]	Goodwill -The purchase price of an acquired business is allocated to the tangible assets, financial assets and separately recognized intangible assets acquired less liabilities assumed based upon their respective fair values, with the excess recorded as goodwill. We review goodwill at least annually for impairment, or whenever events or circumstances indicate that the carrying value of long-lived assets may not be fully recoverable.
Other Intangible Assets [Policy Text Block]	Other Intangible Assets -Contract rights and other intangible assets are amortized primarily using the pattern of benefits method over periods ranging from one to twenty-five years . We account for the cost of computer software developed or obtained for internal use in accordance with ASC 350-985 , Intangibles - Goodwill and Other - Software . These capitalized software costs are included in other intangible assets, net. We account for software development costs related to software products for sale, lease or otherwise marketed in accordance with ASC 985-20 , Software - Costs of Software to Be Sold, Leased, or Marketed . For projects fully funded by us, development costs are capitalized from the point of demonstrated technological feasibility until the point in time that the product is available for general release to customers. Once the product is available for general release, capitalized costs are amortized based on units sold or on a straight-line basis over a five -year period or other such shorter period as may be required.
Impairment of Long-Lived Assets [Policy Text Block]	Impairment of Long-Lived Assets- Whenever events or changes in circumstances indicate that the carrying amount of long-lived assets may not be fully recoverable, we evaluate the probability that future undiscounted net cash flows will be less than the carrying amount of the assets. If any impairment were indicated as a result of this review, we would recognize a loss based on the amount by which the carrying amount exceeds the estimated fair value.
Employee Supplemental Savings Plan Assets [Policy Text Block]	Employee Supplemental Savings Plan (ESSP) Assets -We maintain several non-qualified defined contribution supplemental retirement plans for certain key employees that are accounted for in accordance with ASC 710-10-05 , Compensation - General - Deferred Compensation - Rabbi Trust , as the underlying assets are held in rabbi trusts with investments directed by the respective employee. A rabbi trust is a grantor trust generally set up to fund compensation for a select group of management and the assets of this trust are available to satisfy the claims of general creditors in the event of bankruptcy of us. The assets held by the rabbi trusts are recorded at cash surrender value in our consolidated financial statements as ESSP assets with a related liability to employees recorded as a deferred compensation liability in accrued retirement.
Billings In Excess of Revenue Earned [Policy Text Block]	Billings In Excess of Revenue Earned -We receive advances and milestone payments from customers that exceed the revenues earned to date. We classify such items as current liabilities.
Stock-based Compensation [Policy Text Block]	Stock-based Compensation -We account for stock-based compensation in accordance with ASC 718 , Compensation - Stock Compensation , which requires the use of a valuation model to calculate the fair value of stock-based awards. We have elected to use the Black-Scholes-Merton pricing model to determine fair value of stock options on the dates of grant for our stock options. The fair value is included in operating expenses or capitalized, as appropriate, straight-line over the period in which service is provided in exchange for the award. The grant date fair value of the restricted stock is equal to the closing market price of our common stock on the date of grant. The compensation expense for restricted stock is recognized over the service period and is based on the grant date fair value of the shares. The grant date fair value of the restricted stock unit (RSU) is equal to the closing market price of our common stock on the grant date less the present value of dividends expected to be awarded during the service period. We recognize the grant date fair value of RSUs of shares we expect to issue as compensation expense ratably over the requisite service period. We account for forfeitures as they occur.
Income Taxes [Policy Text Block]	Income Taxes -We account for income taxes in accordance with ASC 740 , Income Taxes . Under this method, deferred income taxes are determined based on the estimated future tax effects of differences between the financial statement and tax bases of assets and liabilities given the provisions of enacted tax laws. Deferred income tax provisions and benefits are based on changes to the assets or liabilities from year-to-year. In providing for deferred taxes, we consider tax regulations of the jurisdictions in which we operate, estimates of future taxable income and available tax planning strategies. If tax regulations, operating results or the ability to implement tax-planning strategies vary, adjustments to the carrying value of deferred tax assets and liabilities may be required. Valuation allowances are recorded related to deferred tax assets based on the “more likely than not” criteria. We recognize the financial statement benefit of a tax position only after determining that the relevant tax authority would “more likely than not” sustain the position following an audit. For tax positions meeting the “more likely than not” threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority.
Foreign-Currency Translation [Policy Text Block]	Foreign-Currency Translation -All assets and liabilities of foreign subsidiaries are translated into U.S. dollars at fiscal year-end exchange rates. Income and expense items are translated at average monthly exchange rates prevailing during the fiscal year. The resulting translation adjustments are recorded as a component of accumulated other comprehensive income (loss).
Comprehensive Income (Loss) [Policy Text Block]	Comprehensive Income (Loss) -Comprehensive income (loss) consists of net income; translation adjustments, net of tax; and actuarial gain (loss) on defined benefit pension plan, net of tax.
Fair Value of Financial Instruments [Policy Text Block]	Fair Value of Financial Instruments -The carrying value of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair value because of the short-term nature of these amounts.
Variable Interest Entities [Policy Text Block]	Variable Interest Entities (VIEs) -We determine whether we have a controlling financial interest in a VIE. The reporting entity with a variable interest or interest that provides the reporting entity with a controlling financial interest in a VIE will have both (a) the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. We have one entity that has been consolidated as a VIE. The purpose of the entity is to perform on certain U.S. Navy contracts. The maximum amount of loss we are exposed to as of December 31, 2017 was not material to our consolidated financial statements.
Investments [Policy Text Block]	Investments -Investments where we have the ability to exercise significant influence, but we do not control, are accounted for under the equity method of accounting and are included in other assets on our consolidated balance sheets. Significant influence typically exists if we have a 20% to 50% ownership interest in the investee. Under this method of accounting, our share of the net earnings or losses of the investee is included in equity in earnings or losses of unconsolidated subsidiaries on our consolidated statement of income. Investments where we have less than 20% ownership interest in the investee and lack the ability to exercise significant influence are accounted for under the cost method. Under the cost method, we recognize our investment in the stock of an investee as an asset. The investment is measured initially at cost. We recognize as income dividends received that are distributed from net accumulated earnings. Dividends received in excess of earnings are considered a return of investment and are recorded as reductions of costs of the investment. Impairment is assessed at the individual investment level. An investment is impaired if the fair value of the investment is less than its costs. If it is determined that the impairment is other than temporary, then an impairment loss is recognized in earnings. The fair value of the investment would become the new cost basis of the investment and will not be adjusted for subsequent recoveries in fair value.
Business Combinations Policy [Policy Text Block]	Business Combinations- The accounting for our business combinations consists of allocating the purchase price to tangible and intangible assets acquired and liabilities assumed based on their estimated fair values, with the excess recorded as goodwill. We have up to one year from the acquisition date to use information as of each acquisition date to adjust the fair value of the acquired assets and liabilities, which may result in material changes to their recorded values with an offsetting adjustment to goodwill.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Recently Adopted ASUs On January 1, 2017, we adopted Accounting Standards Update (ASU) 2016-09, Compensation - Stock Compensation (Topic 718) . The changes in the ASU were adopted prospectively. The ASU requires all excess tax benefits or deficiencies to be recognized as income tax expense or benefit in the consolidated statement of income. Previously, excess tax benefits and deficiencies were recorded as a component of paid-in capital. For the years ended December 31, 2016 and 2015, we recorded $0.1 million and $3.0 million to paid-in capital for the net tax deficiencies related to the exercise of stock options, vested cancellations and the vesting of restricted stock. For the year ended December 31, 2017 , we recorded a net tax benefit of $2.7 million to income tax expense related to the exercise of stock options, vested cancellations and the vesting of restricted stock. The ASU allows a policy election to account for forfeitures as they occur verses requiring a forfeiture estimate. We have elected to account for forfeitures when they occur. Upon transition we recognized a cumulative-effect adjustment to retained earnings of $0.2 million related to previously estimated forfeitures. Under the ASU, excess tax benefits are no longer presented as financing activities in the statement of cash flows. The change in the presentation in the statement of cash flows was applied prospectively beginning January 1, 2017.
ASUs [Policy Text Block]	Recently Issued But Not Yet Adopted ASUs On May 10, 2017, Financial Accounting Standards Board (FASB) has issued Accounting Standards Update (ASU) 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting , which seeks to provide clarity, reduce diversity in practice and reduce cost and complexity when applying the guidance in ASC 718, Compensation—Stock Compensation , regarding a change to the terms or conditions of a share-based payment award. ASU 2017-09 provides guidance concerning which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in ASC 718. Specifically, an entity is to account for the effects of a modification, unless all of the following are satisfied: (1) the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; (2) the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; and (3) the classification of the modified award as an equity instrument or as a liability instrument is the same as the classification of the original award immediately before the original award is modified. The current disclosure requirements in ASC 718 apply regardless of whether an entity is required to apply modification accounting under the amendments in ASU 2017-09. The amendments are effective for annual periods, and for interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted, including adoption in any interim period, for reporting periods for which financial statements have not yet been issued. We do not expect the adoption of this ASU to have a material effect on our consolidated financial statements. On January 26, 2017, the FASB has issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment , which simplifies the manner in which an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. In computing the implied fair value of goodwill under Step 2, an entity, prior to the amendments in ASU 2017-04, had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities, including unrecognized assets and liabilities, in accordance with the procedure that would be required in determining the fair value of assets acquired and liabilities assumed in a business combination. However, under the amendments in this ASU, an entity should (1) perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and (2) recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, with the understanding that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, ASU 2017-04 removes the requirements for any reporting unit with a zero or negative carrying amount to perform a qualitative assessment and, if it fails such qualitative test, to perform Step 2 of the goodwill impairment test. Finally, this ASU amends the Overview and Background sections of the ASC as part of the FASB’s initiative to unify and improve such sections across Topics and Subtopics. Public entities that are SEC filers should adopt the amendments in this ASU prospectively for their annual, or any interim, goodwill impairment tests in fiscal years beginning after December 15, 2019. Note that early adoption is permitted for all entities for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We will continue to evaluate the effects of this ASU in conjunction with our goodwill impairment tests. On January 5, 2017, the FASB has issued ASU 2017-01, Business Combinations (Topic 805)—Clarifying the Definition of a Business , which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. Under the current implementation guidance in Topic 805, there are three elements of a business: inputs, processes and outputs. While an integrated set of assets and activities (collectively, a “set”) that is a business usually has outputs, outputs are not required to be present. Additionally, all of the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs. The amendments in ASU 2017-01 provide a screen to determine when a set is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If, however, the screen is not met, then the amendments in this ASU (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output and (2) remove the evaluation of whether a market participant could replace missing elements. Finally, the amendments in this ASU narrow the definition of the term “output” so that the term is consistent with the manner in which outputs are described in Topic 606. The amendments are effective for annual periods beginning after December 15, 2017, including interim periods within those periods, with early adoption permissible. We do not expect this ASU to have a material effect on our consolidated financial statements. On August 26, 2016, the FASB issued ASU 2016-15— Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . This ASU addresses the following eight specific cash flow issues: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies (including bank-owned life insurance policies); distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The amendments in ASU 2016-15 become effective for fiscal years that start after December 15, 2017. We plan to apply it retrospectively to all periods presented in our quarterly and annual reports on Form 10-Q and Form 10-K. We plan to apply the equity method of accounting for applicable investments. Therefore, we will make an accounting policy election to classify distributions received from equity method investees using the cumulative earnings approach. Distributions received are considered returns on investment and classified as cash inflows from operating activities, unless the investor’s cumulative distributions received less distributions received in prior periods that were determined to be returns of investment exceed cumulative equity in earnings recognized by the investor (as adjusted for amortization of basis differences). When such an excess occurs, the current-period distribution up to this excess is considered a return of investment and should be classified as cash inflows from investing. We do not expect this ASU to have a material effect on our consolidated financial statements. On February 25, 2016, the FASB issued ASU 2016-02— Leases (Topic 842) . The amendments in this ASU create Topic 842 , Leases , and supersede the leases requirements in Topic 840, Leases . The objective of Topic 842 is to establish the principles that lessees and lessors should apply to report useful information to users of financial statements about the amount, timing and uncertainty of cash flows arising from a lease. This ASU is effective for public entities for annual periods after December 15, 2018, and interim periods therein. Early adoption is permitted for all entities. We are currently evaluating methods of adoption as well as the effect on our consolidated financial statements. However, it is expected to increase total assets and total liabilities for current operating leases that are currently recorded off balance sheet. On May 28, 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. ASU 2014-09 supersedes existing revenue recognition guidance, including ASC 605-35 , Revenue Recognition - Construction-Type and Production-Type Contracts . ASU 2014-09 outlines a single set of comprehensive principles for recognizing revenue under GAAP. Among other things, it requires companies to identify contractual performance obligations and determine whether revenue should be recognized at a point in time or over time. These concepts, as well as other aspects of ASU 2014-09, may change the method and/or timing of revenue recognition for certain of our contracts. ASU 2014-09 may be applied either retrospectively or through the use of a modified-retrospective method. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date. The amendments in ASU 2015-14 deferred the effective date of ASU 2014-09 for all entities by one year. Public business entities should apply the guidance in ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. Several related ASUs have been issued since the issuance of ASU 2014-09. These ASUs, which modify certain sections of ASU 2014-09, are intended to promote a more consistent interpretation and application of the principles outlined in the standard. The adoption of ASU 2014-09 will impact our policies, controls, business processes and information systems. To prepare for the changes in this guidance, we developed a plan for adoption. Based on our plan, we commenced an assessment in 2016 on the impacts of this guidance on a representative sample of our existing contract population. The sample contracts selected covered more than 20% of our existing revenue base and included contracts from all of our various contract types. A majority of the contracts we tested were not impacted by the new guidance. For contracts that were impacted, we identified two primary differences. First, the determination of performance obligations under this ASU has led to a different unit of accounting then we are currently applying. Second, we reassessed whether a contract, or performance obligation, met the definition of a "stand ready to perform" or "series" obligation. Those contracts that do not meet the "stand ready to perform" or "series" definition will be transitioned to revenue recognition model where revenue is recognized over time as the performance obligation is satisfied, primarily based on cost incurred. We expect the impact of these changes to produce a more consistent gross margin period-to-period as the obligations are satisfied. We developed and substantially completed a detailed implementation plan during 2017, which includes, among other things, an update to our policies, development of disclosures, updates to our controls and application of the guidance across our contract population. We will adopt ASU 2014-09 under the modified retrospective method to contracts not substantially complete at January 1, 2018. Under the modified retrospective transition method, we will record a transition adjustment to retained earnings. We estimate the cumulative-effect adjustment to retained earnings to be less than $1 million . Based on the results of our detailed implementation plan, we do not expect the adoption of ASU 2014-09 to have a material effect on our consolidated statement of income or our consolidated statement of cash flows. We do expect a more significant impact from the additional disclosures required under the ASU as well as a change in the presentation of contract assets and liabilities on our consolidated balance sheet. Other ASUs effective after December 31, 2017 are not expected to have a material effect on our consolidated financial statements.

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2017
InfoZen, LLC [Member]
Business Combination Segment Allocation [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table represents the preliminary purchase price allocation for InfoZen (in thousands): Cash and cash equivalents $ 1,406 Receivables 9,434 Prepaid expenses and other 4,245 Goodwill 128,686 Other intangible assets 54,850 Property and equipment 485 Other assets 112 Accounts payable and accrued expenses (8,390 ) Accrued salaries and related expenses (2,893 ) Unearned revenue (4,297 ) Billings in excess of revenue earned (1,018 ) Net assets acquired and liabilities assumed $ 182,620
Business Acquisition, Pro Forma Information [Table Text Block]	The following unaudited pro forma financial information below represents our results of operations for years ended December 31, 2017 had the InfoZen acquisition occurred on January 1, 2017 (in thousands). The unaudited proforma financial information below is not intended to represent or be indicative of our actual consolidated results had we completed the acquisition at January 1, 2017. This information should not be taken as representative of our future consolidated results of operations. Revenues and earnings were immaterial for the prior comparative year. Year Ended December 31, 2017 Revenues $ 1,793,752 Net income $ 118,564 Basic earnings per share $ 3.05 Diluted earnings per share $ 3.03
Edaptive Systems LLC [Member]
Business Combination Segment Allocation [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table represents the purchase price allocation for Edaptive (in thousands): Cash and cash equivalents $ 1,955 Receivables 10,892 Prepaid expenses and other 261 Goodwill 6,193 Other intangible assets 1,689 Property and equipment 502 Other assets 116 Accounts payable and accrued expenses (5,777 ) Accrued salaries and related expenses (2,324 ) Billings in excess of revenue earned (326 ) Net assets acquired and liabilities assumed $ 13,181
Oceans Edge, Inc, Cyber Division [Member]
Business Combination Segment Allocation [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table represents the purchase price allocation for OEC (in thousands): Receivables $ 138 Goodwill 30,090 Other intangible assets 18,000 Property and equipment 69 Accounts payable and accrued expenses (29 ) Accrued salaries and related expenses (586 ) Net assets acquired and liabilities assumed $ 47,682
Knowledge Consulting Group [Member]
Business Combination Segment Allocation [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table represents the purchase price allocation for KCG (in thousands): Cash and cash equivalents $ 658 Receivables 6,532 Prepaid expenses and other 460 Goodwill 47,487 Other intangible assets 13,219 Property and equipment 1,419 Investments 15 Other assets 31 Accounts payable and accrued expenses (1,269 ) Accrued salaries and related expenses (336 ) Billings in excess of revenue earned (2 ) Net assets acquired and liabilities assumed $ 68,214
Welkin Associates, Ltd. [Member]
Business Combination Segment Allocation [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The following table represents the purchase price allocation for Welkin (in thousands): Receivables $ 3,901 Prepaid expenses and other 141 Goodwill 24,436 Other intangible assets 6,350 Property and equipment 100 Accounts payable and accrued expenses (436 ) Accrued salaries and related expenses (492 ) Net assets acquired and liabilities assumed $ 34,000

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The net income available to common stockholders and weighted average number of common shares outstanding used to compute basic and diluted earnings per share for each class of common stock are as follows (in thousands, except per share amounts): Year Ended 2017 2016 2015 Distributed earnings $ 32,709 $ 32,138 $ 31,543 Undistributed earnings 81,432 24,253 19,584 Net income $ 114,141 $ 56,391 $ 51,127 Class A common stock: Basic net income available to common stockholders $ 75,413 $ 36,885 $ 33,145 Basic weighted average common shares outstanding 25,685 24,944 24,317 Basic earnings per share $ 2.94 $ 1.48 $ 1.36 Diluted net income available to common stockholders $ 75,698 $ 36,988 $ 33,197 Effect of potential exercise of stock options 288 202 109 Diluted weighted average common shares outstanding 25,973 25,146 24,426 Diluted earnings per share $ 2.91 $ 1.47 $ 1.36 Class B common stock: Basic net income available to common stockholders $ 38,728 $ 19,506 $ 17,982 Basic weighted average common shares outstanding 13,190 13,192 13,193 Basic earnings per share $ 2.94 $ 1.48 $ 1.36 Diluted net income available to common stockholders $ 38,443 $ 19,403 $ 17,930 Effect of potential exercise of stock options — — — Diluted weighted average common shares outstanding 13,190 13,192 13,193 Diluted earnings per share $ 2.91 $ 1.47 $ 1.36

Receivables (Tables)

Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Schedule of Contract Receivables [Table Text Block]	The components of contract receivables are as follows (in thousands): December 31, 2017 2016 Billed receivables $ 236,113 $ 247,114 Unbilled receivables: Amounts billable 52,745 52,640 Revenues recorded in excess of funding 12,397 20,078 Retainage 16,312 8,353 Allowance for doubtful accounts (6,157 ) (7,508 ) Receivables-net $ 311,410 $ 320,677

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment [Table Text Block]	Major classes of property and equipment are summarized as follows (in thousands): December 31, 2017 2016 Furniture and equipment $ 79,218 $ 51,806 Leasehold improvements 39,022 36,439 Property and equipment-gross 118,240 88,245 Accumulated depreciation and amortization (72,158 ) (65,124 ) Property and equipment-net $ 46,082 $ 23,121

Goodwill and Other Intangible29

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	The changes in the carrying amounts of goodwill during fiscal years 2017 and 2016 were as follows (in thousands): Goodwill Balance Goodwill at December 31, 2015 $ 919,591 Acquisitions 36,283 Goodwill at December 31, 2016 955,874 Acquisitions 128,686 Goodwill at December 31, 2017 $ 1,084,560
Schedule of Other Intangible Assets [Table Text Block]	Other intangible assets consisted of the following (in thousands): December 31, 2017 December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Other intangible assets: Contract and program intangible assets $ 355,932 $ 179,049 $ 176,883 $ 301,082 $ 158,671 $ 142,411 Capitalized software cost for internal use 46,937 29,472 17,465 39,332 26,815 12,517 Other 58 58 — 58 55 3 Total other intangible assets-net $ 402,927 $ 208,579 $ 194,348 $ 340,472 $ 185,541 $ 154,931
Schedule of Other Intangible Assets, Future Amortization Expense [Table Text Block]	We estimate that we will have the following amortization expense for the future periods indicated below (in thousands): Year ending: December 31, 2018 $ 25,472 December 31, 2019 $ 21,013 December 31, 2020 $ 20,172 December 31, 2021 $ 17,443 December 31, 2022 $ 14,843

Commitments and Contingencies30

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	At December 31, 2017 , aggregate future minimum rental commitments under these leases are as follows (in thousands): Total Year ending: December 31, 2018 $ 32,353 December 31, 2019 29,252 December 31, 2020 23,048 December 31, 2021 19,964 December 31, 2022 16,793 Thereafter 18,692 Total $ 140,102

Stockholders Equity and Stock31

Stockholders Equity and Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The following table summarizes weighted-average assumptions used in our calculations of fair value for the years ended December 31, 2017 , 2016 and 2015 : Year Ended 2017 2016 2015 Volatility 25.59 % 23.70 % 26.16 % Expected life of options 3 years 3 years 3 years Risk-free interest rate 1.72 % 1.10 % 1.15 % Dividend yield 2.75 % 2.88 % 3.00 %
Share-based Compensation, Stock Options, Activity [Table Text Block]	The following table summarizes stock option activity for the years ended December 31, 2017 , 2016 and 2015 : Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2014 3,391,032 $ 32.76 $ 4,722 Granted 237,853 $ 30.87 Exercised (284,320 ) $ 27.51 $ 1,348 Cancelled and expired (849,255 ) $ 39.56 Stock options outstanding at December 31, 2015 2,495,310 $ 30.86 $ 3,583 Granted 199,938 $ 34.22 Exercised (1,045,789 ) $ 29.24 $ 8,858 Cancelled and expired (489,040 ) $ 37.91 Stock options outstanding at December 31, 2016 1,160,419 $ 29.93 $ 14,299 Granted 534,030 $ 42.90 Exercised (463,800 ) $ 29.34 $ 7,203 Cancelled and expired (61,241 ) $ 33.80 Stock options outstanding at December 31, 2017 1,169,408 $ 35.88 $ 16,731 3 years Stock options exercisable at December 31, 2017 484,429 $ 29.22 $ 10,156 2 years
Schedule of Non-Vested Share Activity [Table Text Block]	The following table summarizes non-vested stock options for the year ended December 31, 2017 : Number of Shares Weighted Average Fair Value Non-vested stock options at December 31, 2016 562,927 $ 4.66 Granted 534,030 $ 6.75 Vested (367,729 ) $ 4.71 Cancelled (44,249 ) $ 5.11 Non-vested stock options at December 31, 2017 684,979 $ 6.23
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock Activity [Table Text Block]	The following table summarizes the restricted stock activity during the years ended December 31, 2017 and 2016 : Number of Shares Weighted Average Fair Value Non-vested restricted stock at December 31, 2015 21,000 $ 28.98 Granted 18,000 $ 33.84 Vested (21,000 ) $ 28.98 Non-vested restricted stock at December 31, 2016 18,000 $ 33.84 Granted 24,000 $ 37.90 Vested (18,000 ) $ 33.84 Non-vested restricted stock at December 31, 2017 24,000 $ 37.90
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock Activity [Table Text Block]	The following table summarizes the RSU activity during the years ended December 31, 2017 and 2016 : Number of Units Weighted Average Fair Value RSUs at December 31, 2015 93,450 $ 30.84 Granted 132,988 $ 29.50 Forfeited (20,100 ) $ 29.56 RSUs at December 31, 2016 206,338 $ 30.10 Granted 55,830 $ 35.34 Vested (3,300 ) $ 30.60 Forfeited (97,525 ) $ 31.00 RSUs at December 31, 2017 161,343 $ 31.36

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	The domestic and foreign components of income operations before income taxes and equity method investments were as follows (in thousands): Year Ended 2017 2016 2015 Domestic $ 97,718 $ 89,988 $ 85,665 Foreign (476 ) 82 (311 ) Income from operations before income taxes and equity method investments $ 97,242 $ 90,070 $ 85,354
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The provision for income taxes was comprised of the following components (in thousands): Year Ended 2017 2016 2015 Current provision: Federal $ 5,340 $ 13,454 $ 2,714 State 2,523 2,394 1,247 Foreign 38 (45 ) 77 7,901 15,803 4,038 Deferred (benefit) provision: Federal (28,013 ) 17,170 27,817 State 3,313 2,831 5,825 (24,700 ) 20,001 33,642 Non-current (benefit) resulting from allocating tax benefits directly to additional paid in capital and changes in liabilities: Federal (60 ) (1,573 ) (2,568 ) State — (445 ) (746 ) (60 ) (2,018 ) (3,314 ) (Benefit) provision for income taxes $ (16,859 ) $ 33,786 $ 34,366
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The schedule of effective income tax rate reconciliation is as follows: Year Ended 2017 2016 2015 Statutory U.S. Federal tax rate 35.0 % 35.0 % 35.0 % Increase (decrease) in tax rate resulting from: Net deferred tax liability remeasurement (52.0 )% — % — % State taxes—net of Federal benefit 3.9 % 3.4 % 4.8 % Stock-based compensation (2.8 )% — % — % ESSP (1.5 )% (0.7 )% 0.2 % Excess executive compensation 0.4 % 0.7 % 0.5 % Section 199 deductions (0.4 )% (0.4 )% (0.4 )% Other, net 0.1 % (0.5 )% 0.1 % Effective tax rate (17.3 )% 37.5 % 40.2 %
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	A summary of the tax effect of the significant components of deferred income taxes is as follows (in thousands): December 31, 2017 2016 Gross deferred tax liabilities: Goodwill and other assets $ 100,967 $ 131,367 Unbilled receivables 11,693 18,608 Property and equipment 7,303 2,657 Total 119,963 152,632 Gross deferred tax assets: Retirement and other liabilities (20,636 ) (27,258 ) Allowance for potential contract losses and other contract reserves (1,598 ) (3,005 ) Federal and state operating loss carryforwards (1,252 ) (560 ) Less: Valuation allowance 717 272 Total (22,769 ) (30,551 ) Net deferred tax liabilities $ 97,194 $ 122,081
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in thousands): December 31, 2017 2016 2015 Gross unrecognized tax benefits at beginning of year $ 293 $ 519 $ 785 Lapse in statute of limitations (105 ) (285 ) (266 ) Increases in tax positions for current year 32 59 — Gross unrecognized tax benefits at end of year $ 220 $ 293 $ 519

Quarterly Financial Informati33

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Table Text Block]	The following tables set forth selected unaudited quarterly financial data: 2017 March 31, June 30, September 30, December 31, (in thousands, except per share data) Revenues $ 418,374 $ 413,694 $ 422,665 $ 462,285 Operating income $ 24,390 $ 24,935 $ 23,140 $ 25,729 Income from operations before income taxes and equity method investments $ 24,159 $ 24,651 $ 23,114 $ 25,318 Net income $ 15,028 $ 15,561 $ 15,182 $ 68,370 Class A common stock: Basic weighted average common shares outstanding 25,547 25,618 25,684 25,886 Basic earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.75 Diluted weighted average common shares outstanding 25,778 25,827 25,929 26,353 Diluted earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.73 Class B common stock: Basic weighted average common shares outstanding 13,191 13,191 13,191 13,189 Basic earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.75 Diluted weighted average common shares outstanding 13,191 13,191 13,191 13,189 Diluted earnings per share $ 0.39 $ 0.40 $ 0.39 $ 1.73 2016 March 31, June 30, September 30, December 31, (in thousands, except per share data) Revenues $ 390,662 $ 401,354 $ 415,402 $ 394,178 Operating income $ 21,945 $ 24,214 $ 23,500 $ 21,304 Income from operations before income taxes and equity method investments $ 21,708 $ 23,972 $ 23,365 $ 21,025 Net income $ 13,216 $ 14,782 $ 14,664 $ 13,729 Class A common stock: Basic weighted average common shares outstanding 24,476 24,707 25,164 25,423 Basic earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.36 Diluted weighted average common shares outstanding 24,567 24,916 25,429 25,667 Diluted earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.35 Class B common stock: Basic weighted average common shares outstanding 13,192 13,192 13,192 13,191 Basic earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.36 Diluted weighted average common shares outstanding 13,192 13,192 13,192 13,191 Diluted earnings per share $ 0.35 $ 0.39 $ 0.38 $ 0.35

Summary of Significant Accoun34

Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	Jan. 02, 2018USD ($)	Dec. 31, 2017USD ($)Entities	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jan. 01, 2017USD ($)
Accounting Policies [Line Items]
More Likely Than Not Threshold		50.00%
Number of Consolidated Variable Interest Entities | Entities		1
Tax deficiency from the exercise of stock options			$ 0.1	$ 3
Income tax expense for tax benefits related to the exercise of stock options and vested cancellations and the vesting of restricted stock		$ (2.7)
Minimum [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life		1 year
Equity Method Investment, Ownership Percentage		20.00%
Maximum [Member]
Accounting Policies [Line Items]
Maturity Threshold For Including In Cash And Cash Equivalent		3 months
Property, Plant and Equipment, Useful Life		7 years
Equity Method Investment, Ownership Percentage		50.00%
Other Intangible Assets [Member] | Minimum [Member]
Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life		1 year
Other Intangible Assets [Member] | Maximum [Member]
Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life		25 years
Capitalized Software Cost For Sale [Member]
Accounting Policies [Line Items]
Finite-Lived Intangible Asset, Useful Life		5 years
Less than [Member]
Accounting Policies [Line Items]
Cost Method Investment, Ownership Percentage		20.00%
Accounting Standards Update 2016-09 [Member]
Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 0.2
Subsequent Event [Member] | Accounting Standards Update 2014-09 [Member]
Accounting Policies [Line Items]
Cumulative Effect on Retained Earnings, before Tax	$ 1

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
InfoZen, LLC [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed	$ 0.8
Business Combination, Consideration Transferred	$ 182.6
Expected Goodwill Tax Amortization Period	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	18 years
InfoZen, LLC [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 49.2
Finite-Lived Intangible Asset, Useful Life	20 years
InfoZen, LLC [Member] | Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 5.7
Finite-Lived Intangible Asset, Useful Life	1 year
Edaptive Systems LLC [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		$ 0.3
Business Combination, Consideration Transferred	$ 13.2
Expected Goodwill Tax Amortization Period	15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	8 years
Edaptive Systems LLC [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 1.1
Finite-Lived Intangible Asset, Useful Life	10 years
Edaptive Systems LLC [Member] | Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount	$ 0.3
Finite-Lived Intangible Asset, Useful Life	1 year
Oceans Edge, Inc, Cyber Division [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed		1.2
Business Combination, Consideration Transferred		$ 47.7
Expected Goodwill Tax Amortization Period		15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		16 years
Oceans Edge, Inc, Cyber Division [Member] | Technology [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount		$ 3
Finite-Lived Intangible Asset, Useful Life		5 years
Oceans Edge, Inc, Cyber Division [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount		$ 14
Finite-Lived Intangible Asset, Useful Life		20 years
Oceans Edge, Inc, Cyber Division [Member] | Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount		$ 1
Finite-Lived Intangible Asset, Useful Life		1 year
Knowledge Consulting Group [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed			$ 0.3
Business Combination, Consideration Transferred			$ 68.2
Expected Goodwill Tax Amortization Period			15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			14 years
Knowledge Consulting Group [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount			$ 12.4
Finite-Lived Intangible Asset, Useful Life			15 years
Knowledge Consulting Group [Member] | Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount			$ 0.8
Finite-Lived Intangible Asset, Useful Life			1 year
Welkin Associates, Ltd. [Member]
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Cost Expensed			$ 0.7
Business Combination, Consideration Transferred			$ 34
Expected Goodwill Tax Amortization Period			15 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life			14 years
Welkin Associates, Ltd. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount			$ 6
Finite-Lived Intangible Asset, Useful Life			15 years
Welkin Associates, Ltd. [Member] | Backlog [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Asset, Amount			$ 0.4
Finite-Lived Intangible Asset, Useful Life			1 year

Acquisitions (Schedule of Recog

Acquisitions (Schedule of Recognized Identified Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 1,084,560	$ 955,874	$ 919,591
InfoZen, LLC [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	1,406
Receivables	9,434
Prepaid expenses and other	4,245
Goodwill	128,686
Other intangible assets	54,850
Property and equipment	485
Other assets	112
Accounts payable and accrued expenses	(8,390)
Accrued salaries and related expenses	(2,893)
Unearned revenue	(4,297)
Billings in excess of revenue earned	(1,018)
Net assets acquired and liabilities assumed	182,620
Edaptive Systems LLC [Member]
Business Acquisition [Line Items]
Cash and cash equivalents	1,955
Receivables	10,892
Prepaid expenses and other	261
Goodwill	6,193
Other intangible assets	1,689
Property and equipment	502
Other assets	116
Accounts payable and accrued expenses	(5,777)
Accrued salaries and related expenses	(2,324)
Billings in excess of revenue earned	(326)
Net assets acquired and liabilities assumed	$ 13,181
Oceans Edge, Inc, Cyber Division [Member]
Business Acquisition [Line Items]
Receivables		138
Goodwill		30,090
Other intangible assets		18,000
Property and equipment		69
Accounts payable and accrued expenses		(29)
Accrued salaries and related expenses		(586)
Net assets acquired and liabilities assumed		$ 47,682
Knowledge Consulting Group [Member]
Business Acquisition [Line Items]
Cash and cash equivalents			658
Receivables			6,532
Prepaid expenses and other			460
Goodwill			47,487
Other intangible assets			13,219
Property and equipment			1,419
Investments			15
Other assets			31
Accounts payable and accrued expenses			(1,269)
Accrued salaries and related expenses			(336)
Billings in excess of revenue earned			(2)
Net assets acquired and liabilities assumed			68,214
Welkin Associates, Ltd. [Member]
Business Acquisition [Line Items]
Receivables			3,901
Prepaid expenses and other			141
Goodwill			24,436
Other intangible assets			6,350
Property and equipment			100
Accounts payable and accrued expenses			(436)
Accrued salaries and related expenses			(492)
Net assets acquired and liabilities assumed			$ 34,000

Acquisitions Pro Forma Financia

Acquisitions Pro Forma Financials (Details) - InfoZen, LLC [Member] $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / shares
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues | $	$ 1,793,752
Net income | $	$ 118,564
Basic earnings per share | $ / shares	$ 3.05
Diluted earnings per share | $ / shares	$ 3.03

Earnings per Share (Narrative)

Earnings per Share (Narrative) (Details) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Dividend Declared And Paid	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 0.21
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount													265,866	369,300	1,780,222
Options exercised, Number of Shares													(463,800)	(1,045,789)	(284,320)

(Schedule of Earnings Per Share

(Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Earnings Per Share, Basic and Diluted [Line Items]
Distributed earnings									$ 32,709	$ 32,138	$ 31,543
Undistributed earnings									81,432	24,253	19,584
Net income	$ 68,370	$ 15,182	$ 15,561	$ 15,028	$ 13,729	$ 14,664	$ 14,782	$ 13,216	114,141	56,391	51,127
Class A Common Stock [Member]
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders									$ 75,413	$ 36,885	$ 33,145
Basic weighted average common shares outstanding	25,886,000	25,684,000	25,618,000	25,547,000	25,423,000	25,164,000	24,707,000	24,476,000	25,685,000	24,944,000	24,317,000
Basic earnings per share	$ 1.75	$ 0.39	$ 0.40	$ 0.39	$ 0.36	$ 0.38	$ 0.39	$ 0.35	$ 2.94	$ 1.48	$ 1.36
Diluted net income available to common stockholders									$ 75,698	$ 36,988	$ 33,197
Effect of potential exercise of stock options									288,000	202,000	109,000
Diluted weighted average common shares outstanding	26,353,000	25,929,000	25,827,000	25,778,000	25,667,000	25,429,000	24,916,000	24,567,000	25,973,000	25,146,000	24,426,000
Diluted earnings per share	$ 1.73	$ 0.39	$ 0.40	$ 0.39	$ 0.35	$ 0.38	$ 0.39	$ 0.35	$ 2.91	$ 1.47	$ 1.36
Class B Common Stock [Member]
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders									$ 38,728	$ 19,506	$ 17,982
Basic weighted average common shares outstanding	13,189,000	13,191,000	13,191,000	13,191,000	13,191,000	13,192,000	13,192,000	13,192,000	13,190,000	13,192,000	13,193,000
Basic earnings per share	$ 1.75	$ 0.39	$ 0.40	$ 0.39	$ 0.36	$ 0.38	$ 0.39	$ 0.35	$ 2.94	$ 1.48	$ 1.36
Diluted net income available to common stockholders									$ 38,443	$ 19,403	$ 17,930
Effect of potential exercise of stock options									0	0	0
Diluted weighted average common shares outstanding	13,189,000	13,191,000	13,191,000	13,191,000	13,191,000	13,192,000	13,192,000	13,192,000	13,190,000	13,192,000	13,193,000
Diluted earnings per share	$ 1.73	$ 0.39	$ 0.40	$ 0.39	$ 0.35	$ 0.38	$ 0.39	$ 0.35	$ 2.91	$ 1.47	$ 1.36

Receivables (Schedule of Contra

Receivables (Schedule of Contract Receivables) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Billed receivables	$ 236,113	$ 247,114
Unbilled receivables:
Amounts billable	52,745	52,640
Revenues recorded in excess of funding	12,397	20,078
Retainage	16,312	8,353
Allowance for doubtful accounts	(6,157)	(7,508)
Receivables-net	$ 311,410	$ 320,677

Receivables (Narrative) (Detail

Receivables (Narrative) (Details) $ in Millions	Dec. 31, 2017USD ($)
Receivables [Abstract]
Accounts Receivable Not Expected to be Substantially Collected within One Year	$ 1.3
Percentage of Accounts Receivable Not Expected to be Collected Within One Year related to Receivables from Direct Sales to U.S. Government	97.70%

Property and Equipment (Propert

Property and Equipment (Property and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment-gross	$ 118,240	$ 88,245
Accumulated depreciation and amortization	(72,158)	(65,124)
Property and equipment-net	46,082	23,121
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment-gross	79,218	51,806
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment-gross	$ 39,022	$ 36,439

Property and Equipment (Narrati

Property and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation and Amortization Expense	$ 9.5	$ 7.8	$ 8.5

Goodwill and Other Intangible44

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of Intangible Assets	$ 23.5	$ 21.8	$ 21.2

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill balance, period start	$ 955,874	$ 919,591
Acquisitions	128,686	36,283
Goodwill balance, period end	$ 1,084,560	$ 955,874

Goodwill and Other Intangible46

Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 402,927,000	$ 340,472,000
Accumulated Amortization	208,579,000	185,541,000
Net Carrying Amount	194,348,000	154,931,000
Contract and program intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	355,932,000	301,082,000
Accumulated Amortization	179,049,000	158,671,000
Net Carrying Amount	176,883,000	142,411,000
Capitalized software cost for internal use
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	46,937,000	39,332,000
Accumulated Amortization	29,472,000	26,815,000
Net Carrying Amount	17,465,000	12,517,000
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	58,000	58,000
Accumulated Amortization	58,000	55,000
Net Carrying Amount	$ 0	$ 3,000

Goodwill and Other Intangible47

Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets, Future Amortization Expense) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Year ending:
December 31, 2018	$ 25,472
December 31, 2019	21,013
December 31, 2020	20,172
December 31, 2021	17,443
December 31, 2022	$ 14,843

Debt (Revolving Credit Facility

Debt (Revolving Credit Facility) (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Aug. 17, 2017
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt, Weighted Average Interest Rate	2.99%	3.75%
Bank of America Syndicate [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500,000,000
Debt Issuance Cost			$ 2,200,000
Long-term Line of Credit	31,000,000	$ 0
Line of Credit Facility, Average Outstanding Amount	2,700,000	0
Line of Credit Facility, Remaining Borrowing Capacity	453,700,000
Bank of America Syndicate [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	75,000,000		$ 75,000,000
Letters of Credit Outstanding, Amount	15,300,000	$ 23,100,000
Bank of America Syndicate [Member] | Revolving Credit Facility, Swing Line Loan [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 30,000,000
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.25%
Bank of America's Base Rate [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Bank of America's Base Rate [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%

Commitments and Contingencies49

Commitments and Contingencies (Pending Litigation) (Narrative) (Details)	May 19, 2017USD ($)	Dec. 31, 2017USD ($)$ / d	Dec. 31, 2016USD ($)
Loss Contingencies [Line Items]
Loss Contingency Accrual		$ 2,300,000
Loss Contingency, Receivable		2,800,000
Loss Contingency, Range of Possible Loss, Portion Not Accrued		800,000
Loss Contingency, Loss in Period		0
Emotional distress [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value			$ 800,000
Back pay and front pay [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value	$ 1,800,000
Attorney fees and cost [Member] | Plaintiff No. One [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		300,000
Attorney fees and cost [Member] | Plaintiff No. Two [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		300,000
Back pay [Member] | Plaintiff No. One [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		900,000
Back pay [Member] | Plaintiff No. Two [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		$ 500,000
Per Diem Interest Rate [Member] | Plaintiff No. One [Member]
Loss Contingencies [Line Items]
Loss Contingency Damages Awarded Value Per Duration | $ / d		16.92
Per Diem Interest Rate [Member] | Plaintiff No. Two [Member]
Loss Contingencies [Line Items]
Loss Contingency Damages Awarded Value Per Duration | $ / d		9.79
Front Pay [Member] | Plaintiff No. One [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		$ 300,000
Front Pay [Member] | Plaintiff No. Two [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Awarded, Value		$ 200,000

Commitments and Contingencies50

Commitments and Contingencies (Letter of Credit) (Narrative) (Details) - Bank of America Syndicate [Member] - Letter of Credit [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 15.3	$ 23.1
Performance Guarantee [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 15.2

Commitments and Contingencies51

Commitments and Contingencies (Operating Leases) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Rent Expense, Net	$ 36.9	$ 37.4	$ 37.2
Deferred Rent Credit	$ 10.6	$ 11.1

Commitments and Contingencies52

Commitments and Contingencies (Schedule of Future Minimum Rental Payments for Operating Leases) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Year ending:
December 31, 2018	$ 32,353
December 31, 2019	29,252
December 31, 2020	23,048
December 31, 2021	19,964
December 31, 2022	16,793
Thereafter	18,692
Total	$ 140,102

Stockholders Equity and Stock53

Stockholders Equity and Stock-Based Compensation (Narrative) (Details) - USD ($)	Jan. 02, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders Equity and Stock-Based Compensation [Line Items]
Treasury Stock, Shares		244,113	244,113
Class B Share Convertible to Class A Share		1
Preferred Stock, Shares Authorized		20,000,000
Preferred Stock, Par Value Per Share		$ 0.01
Preferred Stock, Shares Outstanding		0	0
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		13,963,435
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Issuance		5,980,594
Allocated Share-based Compensation Expense		$ 6,300,000	$ 3,300,000	$ 4,400,000
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount		0	0	0
Income tax expense for tax benefits related to the exercise of stock options and vested cancellations and the vesting of restricted stock		$ (2,700,000)
Tax deficiency from the exercise of stock options			$ (100,000)	$ (3,000,000)
Share-based Compensation Arrangement by Share-based Award, Award Vesting Period		3 years	3 years	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		5 years	5 years	5 years
Expected Annual Cash Dividend		$ 0.84	$ 0.84	$ 0.84
Granted, Weighted Average Fair Value		$ 6.75	$ 4.60	$ 4.59
Share-based Payment Award, Options, Vested, Fair Value		$ 1,700,000	$ 2,600,000	$ 3,600,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 3,600,000
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition		3 years
Restricted Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		24,000	18,000
Restricted Stock Units (RSUs) [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Award, Award Vesting Period		2 years	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		55,830	132,988
Class A Common Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Common Stock, Shares Authorized		150,000,000	150,000,000
Common Stock, Par Value Per Share		$ 0.01	$ 0.01
Common Stock, Shares Outstanding		26,041,660	25,551,860
Common Stock, Voting Rights		1
Class B Common Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Common Stock, Shares Authorized		50,000,000	50,000,000
Common Stock, Par Value Per Share		$ 0.01	$ 0.01
Common Stock, Shares Outstanding		13,189,245	13,190,745
Common Stock, Voting Rights		10
Maximum [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		8 years	8 years	8 years
Going Private Transaction [Member] | Class A Common Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Common Stock, Voting Rights		1
Going Private Transaction [Member] | Class B Common Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Common Stock, Voting Rights		1
Subsequent Event [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Annual Percentage Increase In Number Of Shares Available For Issuance	1.50%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	588,464
Director [Member] | Restricted Stock [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Award, Award Vesting Period		1 year	1 year
Officer [Member] | Restricted Stock Units (RSUs) [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			26,788
Officer [Member] | Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Award, Award Vesting Period			4 years
Officer [Member] | Maximum [Member] | Restricted Stock Units (RSUs) [Member]
Stockholders Equity and Stock-Based Compensation [Line Items]
Share-based Compensation Arrangement by Share-based Award, Award Vesting Period			5 years

Stockholders Equity and Stock54

Stockholders Equity and Stock-Based Compensation (Schedule of Shared-based Payment Award, Stock Options, Valuation Assumptions) (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders Equity and Stock-Based Compensation [Abstract]
Volatility	25.59%	23.70%	26.16%
Expected life of options	3 years	3 years	3 years
Risk-free interest rate	1.72%	1.10%	1.15%
Dividend yield	2.75%	2.88%	3.00%

Stockholders Equity and Stock55

Stockholders Equity and Stock-Based Compensation (Schedule of Share-based Compensation, Stock Options, Activity) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock options, Number of Shares, Period Start	1,160,419	2,495,310	3,391,032
Granted, Number of Shares	534,030	199,938	237,853
Exercised, Number of Shares	(463,800)	(1,045,789)	(284,320)
Cancelled and expired, Number of Shares	(61,241)	(489,040)	(849,255)
Stock options, Number of Shares, Period End	1,169,408	1,160,419	2,495,310
Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Stock options, Weighted Average Exercise Price, Period Start	$ 29.93	$ 30.86	$ 32.76
Granted, Weighted Average Exercise Price	42.90	34.22	30.87
Exercised, Weighted Average Exercise Price	29.34	29.24	27.51
Cancelled and expired, Weighted Average Exercise Price	33.80	37.91	39.56
Stock options, Weighted Average Exercise Price, Period End	$ 35.88	$ 29.93	$ 30.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock options, Aggregate Intrinsic Value	$ 16,731	$ 14,299	$ 3,583	$ 4,722
Exercised, Aggregate Intrinsic Value	$ 7,203	$ 8,858	$ 1,348
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number	484,429
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price	$ 29.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 10,156
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term	2 years

Stockholders Equity and Stock56

Stockholders Equity and Stock-Based Compensation (Schedule of Non-Vested Share Activity) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested [Roll Forward]
Non-vested stock options, Number of Shares, Period Start	562,927
Granted, Number of Shares	534,030	199,938	237,853
Vested, Number of Shares	(367,729)
Cancelled, Number of Shares	(44,249)
Non-vested stock options, Number of Shares, Period End	684,979	562,927
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested stock options, Weighted Average Fair Value, Period Start	$ 4.66
Granted, Weighted Average Fair Value	6.75	$ 4.60	$ 4.59
Vested, Weighted Average Fair Value	4.71
Cancelled, Weighted Average Fair Value	5.11
Non-vested stock options, Weighted Average Fair Value, Period End	$ 6.23	$ 4.66

Stockholders Equity and Stock57

Stockholders Equity and Stock-Based Compensation (Schedule of Share-based Compensation, Restricted Stock Activity) (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock, Non-vested
Non-vested, Period Start	18,000	21,000
Granted	24,000	18,000
Vested	(18,000)	(21,000)
Non-vested, Period End	24,000	18,000
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock, Weighted Average Fair Value
Non-vested, Weighted Average Fair Value, Period Start	$ 33.84	$ 28.98
Granted, Weighted Average Fair Value	37.90	33.84
Vested, Weighted Average Fair Value	33.84	28.98
Non-vested, Weighted Average Fair Value, Period End	$ 37.90	$ 33.84

Stockholders Equity and Stock58

Stockholders Equity and Stock-Based Compensation Schedule of Share-based Compensation, Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Number of Shares [Roll Forward]
Non-vested, Period Start	206,338	93,450
Granted	55,830	132,988
Vested	(3,300)
Forfeited	(97,525)	(20,100)
Non-vested, Period End	161,343	206,338
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Weighted Average Fair Value
Non-vested, Weighted Average Fair Value, Period Start	$ 30.10	$ 30.84
Granted, Weighted Average Fair Value	35.34	29.50
Vested, Weighted Average Fair Value	30.60
Forfeited, Weighted Average Fair Value	31	29.56
Non-vested, Weighted Average Fair Value, Period End	$ 31.36	$ 30.10

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Plan [Line Items]
Defined Contribution Plan, Other Than Employee Stock Ownership Plan, Contributions	$ 20.6	$ 19.8	$ 18.5
Employee Supplemental Savings Plan (ESSP) Percentage of Annual Base Compensation	75.00%	75.00%	75.00%
Employee Supplemental Savings Plan (ESSP) Percentage of Bonus	100.00%	100.00%	100.00%
Employee Supplemental Savings Plan (ESSP), Employee Contribution	$ 3	$ 2.6	$ 2.8
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Defined Benefit Plan, Benefit Obligation	$ 1.2	$ 1.1

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Non-current Provision (Benefit) for Income Taxes related to Liabilities for Uncertain Tax Positions	$ (0.1)	$ (0.2)	$ (0.3)
Income Taxes Paid, Net of Refunds	15.9	18.1	6.4
Impact of Tax Cut an Jobs Act on Income Taxes	50.6
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	0.2	$ 0.2	$ 0.4
Settlement With Taxing Authority [Member]
Income Tax Contingency [Line Items]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	0.1
State [Member]
Income Tax Contingency [Line Items]
Operating Loss Carryforwards	9.9
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating Loss Carryforwards	$ 3.5

Income Taxes (Schedule of Incom

Income Taxes (Schedule of Income before Income Tax, Domestic and Foreign) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic									$ 97,718	$ 89,988	$ 85,665
Foreign									(476)	82	(311)
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND EQUITY METHOD INVESTMENTS	$ 25,318	$ 23,114	$ 24,651	$ 24,159	$ 21,025	$ 23,365	$ 23,972	$ 21,708	$ 97,242	$ 90,070	$ 85,354

Income Taxes (Schedule of Compo

Income Taxes (Schedule of Components of Income Tax Expense) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current provision:
Federal	$ 5,340,000	$ 13,454,000	$ 2,714,000
State	2,523,000	2,394,000	1,247,000
Foreign	38,000	(45,000)	77,000
Current provision	7,901,000	15,803,000	4,038,000
Deferred (benefit) provision:
Federal	(28,013,000)	17,170,000	27,817,000
State	3,313,000	2,831,000	5,825,000
Deferred (benefit) provision	(24,700,000)	20,001,000	33,642,000
Non-current (benefit) resulting from allocating tax benefits directly to additional paid in capital and changes in liabilities:
Federal	(60,000)	(1,573,000)	(2,568,000)
State	0	(445,000)	(746,000)
Non-current (benefit) resulting from allocating tax benefits directly to additional paid in capital and changes in liabilities	(60,000)	(2,018,000)	(3,314,000)
(Benefit) provision for income taxes	$ (16,859,000)	$ 33,786,000	$ 34,366,000

Income Taxes (Schedule of Effec

Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory U.S. Federal tax rate	35.00%	35.00%	35.00%
Increase (decrease) in tax rate resulting from:
Net deferred tax liability remeasurement	(52.00%)	0.00%	0.00%
State taxes—net of Federal benefit	3.90%	3.40%	4.80%
Stock-based compensation	(2.80%)	0.00%	0.00%
ESSP	(1.50%)	(0.70%)	0.20%
Excess executive compensation	0.40%	0.70%	0.50%
Section 199 deductions	(0.40%)	(0.40%)	(0.40%)
Other, net	0.10%	(0.50%)	0.10%
Effective tax rate	(17.30%)	37.50%	40.20%

Income Taxes (Schedule of Defer

Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Gross deferred tax liabilities:
Goodwill and other assets	$ 100,967	$ 131,367
Unbilled receivables	11,693	18,608
Property and equipment	7,303	2,657
Total	119,963	152,632
Gross deferred tax assets:
Retirement and other liabilities	(20,636)	(27,258)
Allowance for potential contract losses and other contract reserves	(1,598)	(3,005)
Federal and state operating loss carryforwards	(1,252)	(560)
Less: Valuation allowance	717	272
Total	(22,769)	(30,551)
Net deferred tax liabilities	$ 97,194	$ 122,081

Income Taxes (Schedule of Unrec

Income Taxes (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Gross unrecognized tax benefits at beginning of year	$ 293,000	$ 519,000	$ 785,000
Lapse in statute of limitations	(105,000)	(285,000)	(266,000)
Increases in tax positions for current year	32,000	59,000	0
Gross unrecognized tax benefits at end of year	$ 220,000	$ 293,000	$ 519,000

Business Segment and Geograph66

Business Segment and Geographic Area Information (Narrative) (Details) - reportable_segment	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Number of Reportable Segments	1
Revenues [Member] | Government Contracts Concentration Risk [Member]
Segment Reporting Information [Line Items]
Percentage	98.00%	98.00%	99.00%
Revenues [Member] | UNITED STATES
Segment Reporting Information [Line Items]
Percentage	98.00%	98.00%	100.00%
Revenues [Member] | Non-US [Member]
Segment Reporting Information [Line Items]
Percentage	2.00%	2.00%	0.00%

Divestiture of ManTech Cyber 67

Divestiture of ManTech Cyber Solutions International and Investment (MCSI) in CounterTack Inc. (CounterTack) (Details) - USD ($)	Jul. 13, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Noncash or Part Noncash Divestitures [Line Items]
Gain on Disposition of Business		$ 0	$ 0	$ 1,692,000
Transaction costs for disposition of business		$ 0	$ 0	1,174,000
CounterTack Inc. [Member]
Noncash or Part Noncash Divestitures [Line Items]
Payments to Acquire Other Investments	$ 3,800,000
ManTech Cyber Solutions International [Member]
Noncash or Part Noncash Divestitures [Line Items]
Gain on Disposition of Business				1,700,000
Transaction costs for disposition of business				1,200,000
ManTech Cyber Solutions International [Member] | CounterTack Inc. [Member]
Noncash or Part Noncash Divestitures [Line Items]
Noncash or Part Noncash Divestiture, Amount of Consideration Received				$ 6,700,000

Quarterly Financial Informati68

Quarterly Financial Information (Unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Line Items]
Revenues	$ 462,285	$ 422,665	$ 413,694	$ 418,374	$ 394,178	$ 415,402	$ 401,354	$ 390,662	$ 1,717,018	$ 1,601,596	$ 1,550,117
Operating income	25,729	23,140	24,935	24,390	21,304	23,500	24,214	21,945	98,194	90,963	84,886
Income from operations before income taxes and equity method investments	25,318	23,114	24,651	24,159	21,025	23,365	23,972	21,708	97,242	90,070	85,354
Net income	$ 68,370	$ 15,182	$ 15,561	$ 15,028	$ 13,729	$ 14,664	$ 14,782	$ 13,216	$ 114,141	$ 56,391	$ 51,127
Class A Common Stock [Member]
Quarterly Financial Information Disclosure [Line Items]
Basic weighted average common shares outstanding	25,886	25,684	25,618	25,547	25,423	25,164	24,707	24,476	25,685	24,944	24,317
Basic earnings per share	$ 1.75	$ 0.39	$ 0.40	$ 0.39	$ 0.36	$ 0.38	$ 0.39	$ 0.35	$ 2.94	$ 1.48	$ 1.36
Diluted weighted average common shares outstanding	26,353	25,929	25,827	25,778	25,667	25,429	24,916	24,567	25,973	25,146	24,426
Diluted earnings per share	$ 1.73	$ 0.39	$ 0.40	$ 0.39	$ 0.35	$ 0.38	$ 0.39	$ 0.35	$ 2.91	$ 1.47	$ 1.36
Class B Common Stock [Member]
Quarterly Financial Information Disclosure [Line Items]
Basic weighted average common shares outstanding	13,189	13,191	13,191	13,191	13,191	13,192	13,192	13,192	13,190	13,192	13,193
Basic earnings per share	$ 1.75	$ 0.39	$ 0.40	$ 0.39	$ 0.36	$ 0.38	$ 0.39	$ 0.35	$ 2.94	$ 1.48	$ 1.36
Diluted weighted average common shares outstanding	13,189	13,191	13,191	13,191	13,191	13,192	13,192	13,192	13,190	13,192	13,193
Diluted earnings per share	$ 1.73	$ 0.39	$ 0.40	$ 0.39	$ 0.35	$ 0.38	$ 0.39	$ 0.35	$ 2.91	$ 1.47	$ 1.36

Schedule II (Valuation and Qual

Schedule II (Valuation and Qualifying Accounts) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		$ 7,508,000	$ 8,473,000	$ 9,830,000
Charged to Costs and Expenses		0	0	0
Deductions		0	(215,000)	(552,000)
Other	[1]	(1,351,000)	(750,000)	(805,000)
Balance at End of Period		6,157,000	7,508,000	8,473,000
Deferred Tax Asset Valuation
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		272,000	0	64,000
Charged to Costs and Expenses		444,000	272,000	0
Deductions		0	0	0
Other		1,000	0	(64,000)
Balance at End of Period		$ 717,000	$ 272,000	$ 0
[1]	Other represents doubtful account reserves released or recorded as part of net revenues for estimated customer disallowances.