Mantech International (MANT) 10-Q 3 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	3 Months Ended
	Mar. 31, 2019	May 01, 2019
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	MANT
Entity Registrant Name	ManTech International Corp
Entity Central Index Key	0000892537
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Emerging Growth Company	false
Small Reporting Company	false
Class A common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		26,693,060
Class B common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		13,188,045

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($)	Mar. 31, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 120,535,000	$ 5,294,000
Receivables—net	390,851,000	405,378,000
Prepaid expenses	21,356,000	23,398,000
Other current assets	4,776,000	5,915,000
Total Current Assets	537,518,000	439,985,000
Goodwill	1,085,806,000	1,085,806,000
Other intangible assets—net	167,092,000	171,962,000
Operating lease right of use assets	119,807,000	0
Property and equipment—net	54,479,000	51,427,000
Employee supplemental savings plan assets	33,606,000	30,501,000
Investments	11,817,000	11,830,000
Other assets	13,529,000	12,360,000
TOTAL ASSETS	2,023,654,000	1,803,871,000
LIABILITIES
Accounts payable and accrued expenses	128,746,000	126,066,000
Accrued salaries and related expenses	82,384,000	89,058,000
Contract liabilities	28,830,000	28,209,000
Operating lease liabilities—current	26,260,000	0
Total Current Liabilities	266,220,000	243,333,000
Long term debt	96,000,000	7,500,000
Deferred income taxes	111,714,000	108,956,000
Operating lease liabilities—long term	104,465,000	0
Accrued retirement	31,238,000	30,999,000
Other long-term liabilities	830,000	11,889,000
TOTAL LIABILITIES	610,467,000	402,677,000
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY
Additional paid-in capital	508,605,000	506,970,000
Treasury stock	(9,158,000)	(9,158,000)
Retained earnings	913,429,000	903,084,000
Accumulated other comprehensive loss	(90,000)	(102,000)
TOTAL STOCKHOLDERS’ EQUITY	1,413,187,000	1,401,194,000
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	2,023,654,000	1,803,871,000
Class A common stock
STOCKHOLDERS' EQUITY
Common stock	269,000	268,000
TOTAL STOCKHOLDERS’ EQUITY	269,000	268,000
Class B common stock
STOCKHOLDERS' EQUITY
Common stock	132,000	132,000
TOTAL STOCKHOLDERS’ EQUITY	$ 132,000	$ 132,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets Parentheticals - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Treasury stock, Shares	244,113	244,113
Class A common stock
Common stock, Par value per share	$ 0.01	$ 0.01
Common stock, Shares authorized	150,000,000	150,000,000
Common stock, Shares issued	26,916,995	26,817,513
Common stock, Shares outstanding	26,672,882	26,573,400
Class B common stock
Common stock, Par value per share	$ 0.01	$ 0.01
Common stock, Shares authorized	50,000,000	50,000,000
Common stock, Shares issued	13,188,045	13,188,045
Common stock, Shares outstanding	13,188,045	13,188,045

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
REVENUE	$ 501,930	$ 473,236
Cost of services	431,083	403,933
General and administrative expenses	42,315	42,882
OPERATING INCOME	28,532	26,421
Interest expense	(484)	(734)
Interest income	190	15
Other income (expense), net	(42)	4
INCOME FROM OPERATIONS BEFORE INCOME TAXES AND EQUITY METHOD INVESTMENTS	28,196	25,706
Provision for income taxes	(7,066)	(5,679)
Equity in earnings (losses) of unconsolidated subsidiaries	(12)	40
NET INCOME	$ 21,118	$ 20,067
Class A common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	$ 0.53	$ 0.51
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	0.53	0.51
Class B common stock
BASIC EARNINGS PER SHARE:
Basic earnings per share	0.53	0.51
DILUTED EARNINGS PER SHARE:
Diluted earnings per share	$ 0.53	$ 0.51

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
NET INCOME	$ 21,118,000	$ 20,067,000
OTHER COMPREHENSIVE INCOME (LOSS):
Cumulative-effect adjustment for adoption of Accounting Standards Update 2018-02	(24,000)	0
Translation adjustments, net of tax	12,000	11,000
Total other comprehensive income (loss)	(12,000)	11,000
COMPREHENSIVE INCOME	$ 21,106,000	$ 20,078,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Stockholders' Equity Statement - 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 period at Dec. 31, 2017		$ 263,000	$ 132,000	$ 492,030,000	$ (9,158,000)	$ 860,027,000	$ (320,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises		2,000		5,994,000
Stock-based compensation expense	$ 1,054,000	1,000		1,053,000
Payment consideration to tax authority on employees' behalf				(2,723,000)
Net income	20,067,000					20,067,000
Dividends						(9,867,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2018-02	0					0
Cumulative-effect adjustment for adoption of Accounting Standards Update 2014-09						587,000
Translation adjustments, net of tax	11,000						11,000
At end of period at Mar. 31, 2018	1,358,099,000	266,000	132,000	496,354,000	(9,158,000)	870,814,000	(309,000)
At beginning of period at Dec. 31, 2018	1,401,194,000	268,000	132,000	506,970,000	(9,158,000)	903,084,000	(102,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises		1,000		1,681,000
Stock-based compensation expense	1,311,000	0		1,311,000
Payment consideration to tax authority on employees' behalf				(1,357,000)
Net income	21,118,000					21,118,000
Dividends						(10,749,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2018-02	(24,000)					(24,000)
Cumulative-effect adjustment for adoption of Accounting Standards Update 2014-09						0
Translation adjustments, net of tax	12,000						12,000
At end of period at Mar. 31, 2019	$ 1,413,187,000	$ 269,000	$ 132,000	$ 508,605,000	$ (9,158,000)	$ 913,429,000	$ (90,000)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM (USED IN) OPERATING ACTIVITIES:
Net income	$ 21,118,000	$ 20,067,000
Adjustments to reconcile net income to net cash flow from (used in) operating activities:
Depreciation and amortization	12,644,000	13,209,000
Noncash lease expense	6,814,000	0
Deferred income taxes	2,758,000	3,969,000
Stock-based compensation expense	1,311,000	1,054,000
Equity in (earnings) losses of unconsolidated subsidiaries	12,000	(40,000)
Change in assets and liabilities—net of effects from acquired businesses:
Receivables—net	14,527,000	(45,458,000)
Prepaid expenses	(1,463,000)	(5,616,000)
Other current assets	1,139,000	2,361,000
Employee supplemental savings plan asset	(3,105,000)	255,000
Accounts payable and accrued expenses	3,923,000	4,980,000
Accrued salaries and related expenses	(6,674,000)	(9,873,000)
Contract liabilities	621,000	(397,000)
Operating lease liabilities	(6,752,000)	0
Accrued retirement	239,000	(2,224,000)
Other	227,000	(302,000)
Net cash flow from (used in) operating activities	47,339,000	(18,015,000)
CASH FLOWS FROM (USED IN) INVESTING ACTIVITIES:
Purchases of property and equipment	(7,238,000)	(6,574,000)
Deferred contract costs	(1,892,000)	(295,000)
Investment in capitalized software for internal use	(1,024,000)	(2,097,000)
Net cash used in investing activities	(10,154,000)	(8,966,000)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Borrowing under revolving credit facility	240,000,000	191,000,000
Repayments under revolving credit facility	(151,500,000)	(156,500,000)
Dividends paid	(10,744,000)	(9,861,000)
Proceeds from exercise of stock options	1,682,000	5,996,000
Payment consideration to tax authority on employees' behalf	(1,357,000)	(2,723,000)
Principal paid on financing leases	(25,000)	0
Net cash flow from financing activities	78,056,000	27,912,000
NET CHANGE IN CASH AND CASH EQUIVALENTS	115,241,000	931,000
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	5,294,000	9,451,000
CASH AND CASH EQUIVALENTS, END OF PERIOD	120,535,000	10,382,000
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for interest	378,000	647,000
Cash paid for income taxes, net of refunds	(6,000)	(3,000)
Noncash investing and financing activities:
Operating lease liabilities arising from obtaining right of use assets	7,924,000	0
Finance lease liabilities arising from obtaining right of use assets	203,000	0
Capital expenditures incurred but not yet paid	$ 1,358,000	$ 3,653,000

Description of the Business (No

Description of the Business (Notes)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business [Text Block]	Description of the Business

Basis of Presentation (Notes)

Basis of Presentation (Notes)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation [Text Block]	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and note disclosures normally included in the annual financial statements, prepared in accordance with accounting principles generally accepted in the U.S., have been condensed or omitted pursuant to those rules and regulations. The preparation of these condensed consolidated financial statements requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenue and expenses. We recommend that you read these condensed consolidated financial statements in conjunction with the audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018

Revenue from Contracts with Cus

Revenue from Contracts with Customers (Notes)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Text Block]	Revenue from Contracts with Customers On January 1, 2018, we adopted Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers using the modified retrospective method applied to those contracts that were not substantially complete as of January 1, 2018. ASC 606 outlines a five-step model whereby revenue is recognized as performance obligations within the contract are satisfied. ASC 606 also requires new, expanded disclosures regarding revenue recognition. We recognized the cumulative effect of adopting ASC 606 as an increase to the 2018 opening balance of retained earnings in the amount of $0.8 million , with the impact primarily related to fixed-price contracts. We derive revenue from contracts with customers primarily from contracts with the U.S. government in the areas of defense, intelligence, homeland security and other federal civilian agencies. Substantially all of our revenue is derived from services and solutions provided to the U.S. government or to prime contractors supporting the U.S. government, including services by our employees and our subcontractors, and solutions that include third-party hardware and software that we purchase and integrate as a part of our overall solutions. Customer requirements may vary from period-to-period depending on specific contract and customer requirements. We provide our services and solutions under three types of contracts: cost-reimbursable, fixed-price and time-and-materials. Under cost-reimbursable contracts, we are reimbursed for costs that are determined to be reasonable, allowable and allocable to the contract and paid a fee representing the profit margin negotiated between us and the contracting agency, which may be fixed or performance based. Under fixed-price contracts, we perform specific tasks for a fixed price. Fixed-price contracts may include either a product delivery or specific service performance over a defined period. Under time-and-materials contracts, we are reimbursed for labor at fixed hourly rates and generally reimbursed separately for allowable materials, costs and expenses at cost. We typically recognize revenue for time and material contracts under the "right to invoice" model. For contracts that do not meet the criteria to measure performance as a right to invoice, or under the series guidance, we utilize an Estimate at Completion process to measure progress toward completion. We typically estimate progress towards completion based on cost incurred or direct labor incurred. As part of this process, we review information including, but not limited to, any outstanding key contract matters, progress towards completion and the related program schedule, identified risks and opportunities and the related changes in estimates of revenue and costs. The risks and opportunities include judgments about the ability and cost to achieve the contract milestones and other technical contract requirements. We make assumptions and estimates regarding labor productivity and availability, the complexity of the work to be performed, the availability of materials, the length of time to complete the performance obligation, execution by our subcontractors, the availability and timing of funding from our customer and overhead cost rates, among other variables. A significant change in one or more of these estimates could affect the timing in which we recognize revenue on our contracts. For the three months ended March 31, 2019 , the aggregate impact of adjustments in contract estimates increased our revenue by $3.2 million . We have one reportable segment. Our U.S. government customers typically exercise independent decision-making and contracting authority. Offices or divisions within an agency or department of the U.S. government may directly, or through a prime contractor, use our services as a separate customer as long as the customer has independent decision-making and contracting authority within its organization. We treat sales to U.S. government customers as sales within the U.S. regardless of where the services are performed. The following tables disclose revenue (in thousands) by contract type, customer, prime or subcontractor and geography for the periods presented. Three months ended 2019 2018 Cost-reimbursable $ 359,765 $ 309,047 Fixed-price 47,102 116,171 Time-and-materials 95,063 48,018 Revenue $ 501,930 $ 473,236 Three months ended 2019 2018 Department of Defense and intelligence agencies $ 389,829 $ 333,914 Federal civilian agencies 101,188 128,233 State agencies, international agencies and commercial entities 10,913 11,089 Revenue $ 501,930 $ 473,236 Three months ended 2019 2018 Prime contractor $ 446,519 $ 422,233 Subcontractor 55,411 51,003 Revenue $ 501,930 $ 473,236 Three months ended 2019 2018 U.S. $ 494,660 $ 466,025 International 7,270 7,211 Revenue $ 501,930 $ 473,236 The following table discloses contract receivables (in thousands): March 31, 2019 December 31, 2018 Billed receivables $ 304,214 $ 301,716 Unbilled receivables 92,843 109,895 Allowance for doubtful accounts (6,206 ) (6,233 ) Receivables—net $ 390,851 $ 405,378 Receivables at March 31, 2019 are expected to be substantially collected within one year except for approximately $0.9 million , of which 100% is related to receivables from sales to the U.S. government or from contracts in which we acted as a subcontractor to other contractors selling to the U.S. government. We have one contract which accounts for 11.4% of our accounts receivable balance. We do not believe that we have significant exposure to credit risk as billed receivable and unbilled receivables 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. The following table discloses contract liabilities (in thousands): March 31, 2019 December 31, 2018 Contract liabilities $ 28,830 $ 28,209 For the three months ended March 31, 2019 , the amount of revenue that was included in the opening contract liabilities balance was $18.0 million . The remaining performance obligation as of March 31, 2019 is $2.7 billion . The following table discloses when we expect to recognize the remaining performance obligation as revenue (in billions): For the remaining nine months ending December 31, 2019 For the year ending December 31, 2020 December 31, 2021 Thereafter $ 1.4 $ 0.8 $ 0.4 $ 0.1

Leases (Notes)

Leases (Notes)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lease Disclosure [Text Block]	Leases The Financial Accounting Standards Board (FASB) issued ASC 842, Leases , to increase transparency and comparability among organizations by requiring the recognition of right of use (ROU) assets and lease liabilities on the balance sheet. Most prominent among the changes in ASC 842 is the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Under the standard, disclosures are required to meet the objective of enabling users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. We are also required to recognize and measure leases existing at, or entered into after, the beginning of the earliest comparative period presented using a modified retrospective approach, with certain practical expedients available. We elected to adopt ASC 842 on January 1, 2019, resulting in us recording operating lease liabilities of $129.6 million and operating lease right of use assets of $118.7 million . We elected the practical expedient to recognize the lease payments related to short-term leases as profit or loss on a straight-line basis over the lease term and variable lease payments in the period in which the obligation for those payment is incurred. We also elected the following transition related practical expedients: not to reassess whether expired or existing contracts are or contain leases, not to reassess lease classification as determined under ASC 840 and not to reassess initial direct costs from any existing lease. We also elected the practical expedient as an accounting election not to separate nonlease components from lease components on all classes of underlying assets. Our leases include nonlease components such as common area maintenance (CAM), utilities and operating expenses. We also implemented internal controls and key system functionality to enable the preparation of financial information upon adoption. ASC 842 had a material impact on our condensed consolidated balance sheets, but did not have an impact on our condensed consolidated income statements. The most significant impact was the recognition of ROU assets and lease liabilities for operating leases, while our accounting for finance leases remained substantially unchanged. We determine if a contract is or contains a lease at inception. A contract is or contains a lease if the contract conveys the right to control the use of identified property or equipment (an identified asset) for a period of time in exchange for consideration. We have the right to control the use of the identified asset when we have both of the following: the right to obtain substantially all of the economic benefits from use of the identified asset and the right to direct the use of the identified asset. In making this determination, we consider all relevant facts and circumstances. We reassess whether a contract is or contains a lease only if the terms and conditions of the contract are changed. We account for lease components and nonlease components associated with a lease as a single lease component. Operating leases are included in Operating lease ROU assets, Operating lease liabilities—current and Operating lease liabilities—long term on our condensed consolidated balance sheets. Finance leases are included in Property and equipment—net, Accounts payable and other accrued expenses and Other long-term liabilities on our condensed consolidated balance sheets. Our ROU asset is recognized as the lease liability, any initial indirect costs and any prepaid lease payments, less any lease incentives. Our lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. Our lease payments consist of amounts relating to the use of the underlying asset during the lease term, specifically fixed payments, payment to be made in optional periods when we are reasonably certain to exercise an option to extend the lease or not to exercise an option to terminate the lease and the amounts probable of being owned by us under residual guarantees. Our variable lease payments are excluded in measuring ROU asset and lease liability because they do not depend on an index or a rate or are not in substance fixed payments. We exclude lease incentives and initial direct cost incurred from our lease payments. Our leases typically do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of future payments. For operating leases, after lease commencement, we measure our lease liability for each period at the present value of any remaining lease payments, discounted by using the rate determined at lease commencement. In our condensed consolidated statement of income, we recognize a single operating lease expense calculated on a straight-line basis over the remaining lease term. The amortization of the ROU asset increases each year as a result of the declining lease liability balance. Variable lease payments are not recognized in the measurement of the lease liability - they are recognized in the period in which the related obligation has been incurred. For finance leases, after lease commencement, we measure our lease liability by using the effective interest rate method. In each period, the lease liability will be increased to reflect the interest that is accrued on the related lease liability by using the appropriate discount rate, offset by a decrease in the lease liability resulting from the periodic lease payments. We recognize the ROU asset at cost, reduced by any accumulated depreciation. The ROU asset is depreciated on a straight-line basis. Together, the interest expense and amortization expense result in a front-loaded expense profile. We will present interest expense and depreciation expense separately on our condensed consolidated statement of income. We have operating and finance leases for real estate, transportation vehicles and equipment. Our variable lease payments do not depend on an index or a rate or are not in substance fixed payments. Our leases have remaining lease terms of 0.1 years to 11 years , some of which include options to extend the leases for up to 14 years , and some of which include options to terminate the leases within 1 year . Our transportation vehicles and equipment leases include a residual value guarantee, which is a guarantee made to the lessor that the value of the underlying asset returned to the lessor at the end of the lease will be at least a specific amount. We sublease some of our real estate lease space, resulting in sublease income of $23 thousand as of the three months ended March 31, 2019 . We do not have any leases that have not yet commenced due to construction or design of the underlying asset. We recognize payments related to short-term leases (less than one year) as profit or loss on a straight-line basis over the lease term and variable leases payments in the period in which the obligation for those payment is incurred. As such, our short-term lease expense as of March 31, 2019 under ASC 842 was $1.4 million . For the three months ended March 31, 2019 , we incurred variable lease costs of $0.5 million . The balance sheet information related to our leases was as follows (dollars in thousands): March 31, 2019 Operating Leases Operating lease right of use assets $ 119,807 Operating lease liabilities—current $ 26,260 Operating lease liabilities—long term 104,465 Total operating lease liabilities $ 130,725 Finance Leases Property and equipment—gross $ 504 Accumulated depreciation (109 ) Property and equipment—net $ 395 Accounts payable and other accrued expenses $ 112 Other long-term liabilities 293 Total finance lease liabilities $ 405 The components of lease expense were as follows (in thousands): Three months ended, Operating lease expenses $ 7,789 Depreciation of right of use assets $ 110 Interest on lease liabilities 9 Finance lease expenses $ 119 The weighted average information related to leases was a follows: March 31, 2019 Weighted Average Remaining Lease Term Operating leases 5 years Finance leases 4 years Weighted Average Discount Rate Operating leases 4 % Finance leases 5 % Future minimum lease payments under non-cancellable leases as of March 31, 2019 were as follows (in thousands): Operating Leases Financing Leases For the nine months ended December 31, 2019 $ 22,331 $ 118 2020 31,704 135 2021 28,610 115 2022 24,941 109 2023 20,661 12 Thereafter 16,404 — Total future minimum lease payments 144,651 489 Less imputed interest (13,926 ) (84 ) Total $ 130,725 $ 405

Earnings Per Share (Notes)

Earnings Per Share (Notes)	3 Months Ended
	Mar. 31, 2019
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 three months ended March 31, 2019 and 2018 , we declared and paid quarterly dividends in the amount of $0.27 per share and $0.25 per share, respectively, 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): Three months ended 2019 2018 Distributed earnings $ 10,749 $ 9,867 Undistributed earnings 10,369 10,200 Net income $ 21,118 $ 20,067 Class A common stock: Basic net income available to common stockholders $ 14,116 $ 13,333 Basic weighted average common shares outstanding 26,584 26,115 Basic earnings per share $ 0.53 $ 0.51 Diluted net income available to common stockholders $ 14,157 $ 13,403 Effect of potential exercise of stock options 235 410 Diluted weighted average common shares outstanding 26,819 26,525 Diluted earnings per share $ 0.53 $ 0.51 Class B common stock: Basic net income available to common stockholders $ 7,002 $ 6,734 Basic weighted average common shares outstanding 13,188 13,189 Basic earnings per share $ 0.53 $ 0.51 Diluted net income available to common stockholders $ 6,961 $ 6,664 Diluted weighted average common shares outstanding 13,188 13,189 Diluted earnings per share $ 0.53 $ 0.51 For the three months ended March 31, 2019 and 2018 , options to purchase 514,224 shares and 310,745 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 three months ended March 31, 2019 and 2018 , there were 51,089 shares and 203,854 shares, respectively, issued from the exercise of stock options. For the three months ended March 31, 2019 and 2018 there were 72,188 shares and 86,233

Property and Equipment (Notes)

Property and Equipment (Notes)	3 Months Ended
	Mar. 31, 2019
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): March 31, December 31, Furniture and equipment $ 105,934 $ 97,577 Leasehold improvements 43,529 43,065 Finance leases 504 — Property and equipment—gross 149,967 140,642 Accumulated depreciation and amortization (95,488 ) (89,215 ) Property and equipment—net $ 54,479 $ 51,427 Depreciation and amortization expense related to property and equipment for the three months ended March 31, 2019 and 2018 was $6.3 million and $5.9 million

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets (Notes)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets [Text Block]	Goodwill and Other Intangible Assets There was no change in the carrying amount of goodwill during the three months ended March 31, 2019 . The change in the carrying amount of goodwill during the year ended December 31, 2018 is as follows (in thousands): Goodwill Balance Goodwill at December 31, 2017 $ 1,084,560 Acquisition fair value adjustment 1,246 Goodwill at December 31, 2018 $ 1,085,806 Other intangible assets consisted of the following (in thousands): March 31, 2019 December 31, 2018 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 $ 205,977 $ 149,955 $ 355,932 $ 201,298 $ 154,634 Capitalized software cost for internal use 51,836 34,699 17,137 50,925 33,597 17,328 Total other intangible assets—net $ 407,768 $ 240,676 $ 167,092 $ 406,857 $ 234,895 $ 171,962 Amortization expense relating to intangible assets for the three months ended March 31, 2019 and 2018 was $5.8 million and $7.1 million . We estimate that we will have the following amortization expense for the future periods indicated below (in thousands): For the remaining nine months ending December 31, 2019 $ 16,814 For the year ending: December 31, 2020 $ 21,758 December 31, 2021 $ 19,028 December 31, 2022 $ 16,434 December 31, 2023 $ 13,464 December 31, 2024 $ 12,199

Debt (Notes)

Debt (Notes)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt [Text Block]	Debt Revolving Credit Facility —We maintain a credit facility 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 . Borrowings under our credit agreement are collateralized by substantially all of our assets and those of 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 London Interbank Offer Rate based rate plus market-rate 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 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 three months ended March 31, 2019 and 2018 , we were in compliance with the financial covenants under the credit agreement. There was $96.0 million and $7.5 million outstanding on our revolving credit facility at March 31, 2019 and December 31, 2018 , respectively. The maximum available borrowing under the revolving credit facility at March 31, 2019 was $396.3 million . As of March 31, 2019 , we were contingently liable under letters of credit totaling $7.7 million

Commitments and Contingencies (

Commitments and Contingencies (Notes)	3 Months Ended
	Mar. 31, 2019
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 2016 with no material adjustments. The remaining audits for 2017 through 2018 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. An officer of our Company is a party to a pending arbitration proceeding with a former employer that relates to certain breach of contract claims. Pursuant to indemnification arrangements we have with this officer, we may be exposed to a potential loss related to this claim. Pursuant to applicable accounting standards, we have determined that it is reasonably possible that an unfavorable outcome could cause us to incur a liability/loss under these indemnification arrangements. However, given the nature of the claim, the early stage of the process, the limitations on information and other factual details relating to the claims that are available to us at this time, and management’s intent to contest the matter vigorously, we are unable to make a reasonable estimate of loss at this time. As such, we have not disclosed an amount of potential loss as of March 31, 2019 . We have $7.7 million outstanding on our letter of credit, of which $14 thousand

Stock-Based Compensation (Notes

Stock-Based Compensation (Notes)	3 Months Ended
	Mar. 31, 2019
Share-based Compensation [Abstract]
Stock-Based Compensation [Text Block]	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, among others, stock options, restricted stock and restricted stock units (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 31 st of the previous year. On January 2, 2019 , there were 596,422 additional shares made available for issuance under the Plan. Through March 31, 2019 , the Board of Directors has authorized the issuance of up to 15,148,321 shares under this Plan. Through March 31, 2019 , the remaining aggregate number of shares of our common stock available for future grants under the Plan was 6,685,056 . 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 three months ended March 31, 2019 and 2018 , we recorded $1.3 million and $1.1 million of stock-based compensation expense. No compensation expense of employees with stock awards, including stock-based compensation expense, was capitalized during the periods. For the three months ended March 31, 2019 and 2018 , we recorded $0.2 million and $1.1 million , respectively, to income tax benefit related to 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 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 three months ended March 31, 2019 and 2018 , 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 the fair value of our 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 three months ended March 31, 2019 and 2018 : • 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 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 $1.08 per share. The following table summarizes weighted-average assumptions used in our calculations of fair value for the three months ended March 31, 2019 and 2018 : Three months ended 2019 2018 Volatility 26.99 % 26.34 % Expected life of options 3 years 3 years Risk-free interest rate 2.39 % 2.46 % Dividend yield 2.00 % 2.00 % Stock Option Activity —The weighted-average fair value of options granted during the three months ended March 31, 2019 and 2018 , as determined under the Black-Scholes-Merton valuation model, was $10.04 and $9.96 , respectively. Option grants that vested during the three months ended March 31, 2019 and 2018 had a combined fair value of $1.2 million and $0.7 million , respectively. The following table summarizes stock option activity for the year ended December 31, 2018 and the three months ended March 31, 2019 : Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2017 1,169,408 $ 35.88 $ 16,731 Granted 466,828 $ 54.87 Exercised (420,524 ) $ 30.85 $ 12,411 Cancelled and expired (122,312 ) $ 43.85 Stock options outstanding at December 31, 2018 1,093,400 $ 45.34 $ 8,776 Granted 250,231 $ 53.52 Exercised (51,089 ) $ 32.61 $ 1,079 Cancelled and expired (21,265 ) $ 49.48 Stock options outstanding at March 31, 2019 1,271,277 $ 47.39 $ 8,846 4 years Stock options exercisable at March 31, 2019 423,532 $ 38.93 $ 6,392 3 years The following table summarizes non-vested stock options for the three months ended March 31, 2019 : Number of Shares Weighted Average Fair Value Non-vested stock options at December 31, 2018 774,402 $ 8.77 Granted 250,231 $ 10.04 Vested (157,473 ) $ 7.38 Cancelled (19,415 ) $ 8.95 Non-vested stock options at March 31, 2019 847,745 $ 9.40 Unrecognized compensation expense related to non-vested awards was $7.3 million as of March 31, 2019 , which is expected to be recognized over a weighted-average period of 2 years . 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 on the one year anniversary of the grant date. The related compensation expense is recognized over the service period and is based on the grant date fair value of the stock. 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 — There was no restricted stock activity during the three months ended March 31, 2019 . The following table summarizes the restricted stock activity during the year ended December 31, 2018 . Number of Shares Weighted Average Fair Value Non-vested restricted stock at December 31, 2017 24,000 $ 37.90 Granted 24,000 $ 52.83 Vested (28,000 ) $ 40.03 Non-vested restricted stock at December 31, 2018 20,000 $ 52.83 RSUs —Under the Plan, we have 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 have no voting rights until the RSUs vest. Employees who are granted RSUs do not receive dividend payments during the vesting period. Our employees have been granted performance-based RSUs and time-based RSUs. Performance-based RSUs result in the delivery of shares only if (a) performance criteria is met and (b) the employee remains employed, in good standing, through the date of the performance period. Time-based RSUs vest in one-third increments on the first, second and third anniversaries of 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 —For performance-based RSUs that vested in 2019 and 2018 , each RSU awarded resulted in the issuance of 1.5 shares, which were issued net of applicable payroll tax withholdings. The following table summarizes the non-vested RSU activity during the year ended December 31, 2018 and the three months ended March 31, 2019 : Number of Units Weighted Average Fair Value Non-vested RSUs at December 31, 2017 161,343 $ 31.36 Granted 76,713 $ 53.97 Vested (87,200 ) $ 28.40 Forfeited (13,260 ) $ 38.98 Non-vested RSUs at December 31, 2018 137,596 $ 45.11 Granted 88,955 $ 51.60 Vested (53,688 ) $ 40.56 Forfeited (3,267 ) $ 52.09 Non-vested RSUs at March 31, 2019 169,596 $ 49.81

Subsequent Event (Notes)

Subsequent Event (Notes)	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Event Management has evaluated subsequent events after the balance sheet date through the financial statements issuance date for appropriate accounting and disclosure. Acquisition of Kforce Government Solutions On April 1, 2019, we completed the acquisition of Kforce Government Solutions (KGS). KGS was a wholly owned subsidiary of the publicly traded commercial technology and staffing company Kforce, Inc. KGS provides IT solutions, transformation and management consulting, data analytics - most notably in the healthcare IT market. This acquisition will also expand our presence with important customers such as the Department of Veteran Affairs (VA). As specialists in serving the IT needs of defense and federal civilian agencies, KGS complements and builds on our core capabilities and solutions, adding the high-value specialty of health care IT. KGS has delivered innovation and sustainable solutions that transformed technology and business operations to drive enhanced mission execution for these customers. In addition to the VA, KGS's customers include the National Science Foundation, the Federal Reserve System, Defense Threat Reduction Agency, U.S. Air Force and U.S. Transportation Command. We funded the acquisition with cash on hand and borrowings under on revolving credit facility. The preliminary purchase price was $115.0 million

Leases (Policies)

Leases (Policies)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lessee, Leases [Policy Text Block]	We determine if a contract is or contains a lease at inception. A contract is or contains a lease if the contract conveys the right to control the use of identified property or equipment (an identified asset) for a period of time in exchange for consideration. We have the right to control the use of the identified asset when we have both of the following: the right to obtain substantially all of the economic benefits from use of the identified asset and the right to direct the use of the identified asset. In making this determination, we consider all relevant facts and circumstances. We reassess whether a contract is or contains a lease only if the terms and conditions of the contract are changed. We account for lease components and nonlease components associated with a lease as a single lease component. Operating leases are included in Operating lease ROU assets, Operating lease liabilities—current and Operating lease liabilities—long term on our condensed consolidated balance sheets. Finance leases are included in Property and equipment—net, Accounts payable and other accrued expenses and Other long-term liabilities on our condensed consolidated balance sheets. Our ROU asset is recognized as the lease liability, any initial indirect costs and any prepaid lease payments, less any lease incentives. Our lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. Our lease payments consist of amounts relating to the use of the underlying asset during the lease term, specifically fixed payments, payment to be made in optional periods when we are reasonably certain to exercise an option to extend the lease or not to exercise an option to terminate the lease and the amounts probable of being owned by us under residual guarantees. Our variable lease payments are excluded in measuring ROU asset and lease liability because they do not depend on an index or a rate or are not in substance fixed payments. We exclude lease incentives and initial direct cost incurred from our lease payments. Our leases typically do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of future payments. For operating leases, after lease commencement, we measure our lease liability for each period at the present value of any remaining lease payments, discounted by using the rate determined at lease commencement. In our condensed consolidated statement of income, we recognize a single operating lease expense calculated on a straight-line basis over the remaining lease term. The amortization of the ROU asset increases each year as a result of the declining lease liability balance. Variable lease payments are not recognized in the measurement of the lease liability - they are recognized in the period in which the related obligation has been incurred. For finance leases, after lease commencement, we measure our lease liability by using the effective interest rate method. In each period, the lease liability will be increased to reflect the interest that is accrued on the related lease liability by using the appropriate discount rate, offset by a decrease in the lease liability resulting from the periodic lease payments. We recognize the ROU asset at cost, reduced by any accumulated depreciation. The ROU asset is depreciated on a straight-line basis. Together, the interest expense and amortization expense result in a front-loaded expense profile. We will present interest expense and depreciation expense separately on our condensed consolidated statement of income.

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue by Contract Type [Table Text Block]	Three months ended 2019 2018 Cost-reimbursable $ 359,765 $ 309,047 Fixed-price 47,102 116,171 Time-and-materials 95,063 48,018 Revenue $ 501,930 $ 473,236
Revenue by Customer [Table Text Block]	Three months ended 2019 2018 Department of Defense and intelligence agencies $ 389,829 $ 333,914 Federal civilian agencies 101,188 128,233 State agencies, international agencies and commercial entities 10,913 11,089 Revenue $ 501,930 $ 473,236
Revenue by Contractor Type [Table Text Block]	Three months ended 2019 2018 Prime contractor $ 446,519 $ 422,233 Subcontractor 55,411 51,003 Revenue $ 501,930 $ 473,236
Revenue from External Customers by Geographic Areas [Table Text Block]	Three months ended 2019 2018 U.S. $ 494,660 $ 466,025 International 7,270 7,211 Revenue $ 501,930 $ 473,236
Schedule Of Contract Receivables [Table Text Block]	The following table discloses contract receivables (in thousands): March 31, 2019 December 31, 2018 Billed receivables $ 304,214 $ 301,716 Unbilled receivables 92,843 109,895 Allowance for doubtful accounts (6,206 ) (6,233 ) Receivables—net $ 390,851 $ 405,378
Contract with Customer, Asset and Liability [Table Text Block]	The following table discloses contract liabilities (in thousands): March 31, 2019 December 31, 2018 Contract liabilities $ 28,830 $ 28,209
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	The following table discloses when we expect to recognize the remaining performance obligation as revenue (in billions): For the remaining nine months ending December 31, 2019 For the year ending December 31, 2020 December 31, 2021 Thereafter $ 1.4 $ 0.8 $ 0.4 $ 0.1

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lessee, Lease, Balance Sheet [Table Text Block]	The balance sheet information related to our leases was as follows (dollars in thousands): March 31, 2019 Operating Leases Operating lease right of use assets $ 119,807 Operating lease liabilities—current $ 26,260 Operating lease liabilities—long term 104,465 Total operating lease liabilities $ 130,725 Finance Leases Property and equipment—gross $ 504 Accumulated depreciation (109 ) Property and equipment—net $ 395 Accounts payable and other accrued expenses $ 112 Other long-term liabilities 293 Total finance lease liabilities $ 405
Lease, Cost [Table Text Block]	The components of lease expense were as follows (in thousands): Three months ended, Operating lease expenses $ 7,789 Depreciation of right of use assets $ 110 Interest on lease liabilities 9 Finance lease expenses $ 119
Lease Weighted Average Information [Table Text Block]	The weighted average information related to leases was a follows: March 31, 2019 Weighted Average Remaining Lease Term Operating leases 5 years Finance leases 4 years Weighted Average Discount Rate Operating leases 4 % Finance leases 5 %
Schedule of Maturities of Lease Liabilities [Table Text Block]	Future minimum lease payments under non-cancellable leases as of March 31, 2019 were as follows (in thousands): Operating Leases Financing Leases For the nine months ended December 31, 2019 $ 22,331 $ 118 2020 31,704 135 2021 28,610 115 2022 24,941 109 2023 20,661 12 Thereafter 16,404 — Total future minimum lease payments 144,651 489 Less imputed interest (13,926 ) (84 ) Total $ 130,725 $ 405

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
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): Three months ended 2019 2018 Distributed earnings $ 10,749 $ 9,867 Undistributed earnings 10,369 10,200 Net income $ 21,118 $ 20,067 Class A common stock: Basic net income available to common stockholders $ 14,116 $ 13,333 Basic weighted average common shares outstanding 26,584 26,115 Basic earnings per share $ 0.53 $ 0.51 Diluted net income available to common stockholders $ 14,157 $ 13,403 Effect of potential exercise of stock options 235 410 Diluted weighted average common shares outstanding 26,819 26,525 Diluted earnings per share $ 0.53 $ 0.51 Class B common stock: Basic net income available to common stockholders $ 7,002 $ 6,734 Basic weighted average common shares outstanding 13,188 13,189 Basic earnings per share $ 0.53 $ 0.51 Diluted net income available to common stockholders $ 6,961 $ 6,664 Diluted weighted average common shares outstanding 13,188 13,189 Diluted earnings per share $ 0.53 $ 0.51

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment [Table Text Block]	Major classes of property and equipment are summarized as follows (in thousands): March 31, December 31, Furniture and equipment $ 105,934 $ 97,577 Leasehold improvements 43,529 43,065 Finance leases 504 — Property and equipment—gross 149,967 140,642 Accumulated depreciation and amortization (95,488 ) (89,215 ) Property and equipment—net $ 54,479 $ 51,427

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	The change in the carrying amount of goodwill during the year ended December 31, 2018 is as follows (in thousands): Goodwill Balance Goodwill at December 31, 2017 $ 1,084,560 Acquisition fair value adjustment 1,246 Goodwill at December 31, 2018 $ 1,085,806
Schedule of Other Intangible Assets [Table Text Block]	Other intangible assets consisted of the following (in thousands): March 31, 2019 December 31, 2018 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 $ 205,977 $ 149,955 $ 355,932 $ 201,298 $ 154,634 Capitalized software cost for internal use 51,836 34,699 17,137 50,925 33,597 17,328 Total other intangible assets—net $ 407,768 $ 240,676 $ 167,092 $ 406,857 $ 234,895 $ 171,962
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): For the remaining nine months ending December 31, 2019 $ 16,814 For the year ending: December 31, 2020 $ 21,758 December 31, 2021 $ 19,028 December 31, 2022 $ 16,434 December 31, 2023 $ 13,464 December 31, 2024 $ 12,199

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
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 three months ended March 31, 2019 and 2018 : Three months ended 2019 2018 Volatility 26.99 % 26.34 % Expected life of options 3 years 3 years Risk-free interest rate 2.39 % 2.46 % Dividend yield 2.00 % 2.00 %
Share-based Compensation, Stock Options, Activity [Table Text Block]	The following table summarizes stock option activity for the year ended December 31, 2018 and the three months ended March 31, 2019 : Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Weighted Average Remaining Contractual Life Stock options outstanding at December 31, 2017 1,169,408 $ 35.88 $ 16,731 Granted 466,828 $ 54.87 Exercised (420,524 ) $ 30.85 $ 12,411 Cancelled and expired (122,312 ) $ 43.85 Stock options outstanding at December 31, 2018 1,093,400 $ 45.34 $ 8,776 Granted 250,231 $ 53.52 Exercised (51,089 ) $ 32.61 $ 1,079 Cancelled and expired (21,265 ) $ 49.48 Stock options outstanding at March 31, 2019 1,271,277 $ 47.39 $ 8,846 4 years Stock options exercisable at March 31, 2019 423,532 $ 38.93 $ 6,392 3 years
Schedule of Non-vested Share Activity [Table Text Block]	The following table summarizes non-vested stock options for the three months ended March 31, 2019 : Number of Shares Weighted Average Fair Value Non-vested stock options at December 31, 2018 774,402 $ 8.77 Granted 250,231 $ 10.04 Vested (157,473 ) $ 7.38 Cancelled (19,415 ) $ 8.95 Non-vested stock options at March 31, 2019 847,745 $ 9.40
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 year ended December 31, 2018 . Number of Shares Weighted Average Fair Value Non-vested restricted stock at December 31, 2017 24,000 $ 37.90 Granted 24,000 $ 52.83 Vested (28,000 ) $ 40.03 Non-vested restricted stock at December 31, 2018 20,000 $ 52.83
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 non-vested RSU activity during the year ended December 31, 2018 and the three months ended March 31, 2019 : Number of Units Weighted Average Fair Value Non-vested RSUs at December 31, 2017 161,343 $ 31.36 Granted 76,713 $ 53.97 Vested (87,200 ) $ 28.40 Forfeited (13,260 ) $ 38.98 Non-vested RSUs at December 31, 2018 137,596 $ 45.11 Granted 88,955 $ 51.60 Vested (53,688 ) $ 40.56 Forfeited (3,267 ) $ 52.09 Non-vested RSUs at March 31, 2019 169,596 $ 49.81

Revenue from Contracts with C_3

Revenue from Contracts with Customers Narrative (Details) $ in Millions	Jan. 02, 2018USD ($)	Mar. 31, 2019USD ($)Entities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contract with Customer, Asset, Cumulative Catch-up Adjustment to Revenue, Change in Measure of Progress		$ 3.2
Number of Reportable Segments | Entities		1
Contract Receivable, Due after Next Rolling Twelve Months		$ 0.9
Percentage of Accounts Receivable Not Expected to be Collected Within One Year related to Receivables from Direct Sales to U.S. Government		100.00%
Concentration Credit Risk, Percentage, Accounts Receivable		11.40%
Revenue in Opening Contract Liabilities		$ 18
Revenue, Remaining Performance Obligation, Amount		$ 2,700
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, before Tax	$ 0.8

Revenue from Contracts with C_4

Revenue from Contracts with Customers Revenue by Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue by Contract Type [Line Items]
Revenue	$ 501,930	$ 473,236
Cost-reimbursable
Revenue by Contract Type [Line Items]
Revenue	359,765	309,047
Fixed-price
Revenue by Contract Type [Line Items]
Revenue	47,102	116,171
Time-and-materials
Revenue by Contract Type [Line Items]
Revenue	$ 95,063	$ 48,018

Revenue from Contracts with C_5

Revenue from Contracts with Customers Revenue by Customer (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue by Customer [Line Items]
Revenue	$ 501,930	$ 473,236
Department of Defense and intelligence agencies [Member]
Revenue by Customer [Line Items]
Revenue	389,829	333,914
Federal Civilian Agencies [Member]
Revenue by Customer [Line Items]
Revenue	101,188	128,233
State agencies, international agencies and commercial entities [Member]
Revenue by Customer [Line Items]
Revenue	$ 10,913	$ 11,089

Revenue from Contracts with C_6

Revenue from Contracts with Customers Revenue by Contractor Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue by Contractor Type [Line Items]
Revenue	$ 501,930	$ 473,236
Prime contractor
Revenue by Contractor Type [Line Items]
Revenue	446,519	422,233
Subcontractor
Revenue by Contractor Type [Line Items]
Revenue	$ 55,411	$ 51,003

Revenue from Contracts with C_7

Revenue from Contracts with Customers Revenue by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue From External Customers by Geographic Location [Line Items]
Revenue	$ 501,930	$ 473,236
U.S.
Revenue From External Customers by Geographic Location [Line Items]
Revenue	494,660	466,025
International
Revenue From External Customers by Geographic Location [Line Items]
Revenue	$ 7,270	$ 7,211

Revenue from Contracts with C_8

Revenue from Contracts with Customers Schedule of Contract Receivables (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Billed receivables	$ 304,214	$ 301,716
Unbilled receivables	92,843	109,895
Allowance for doubtful accounts	(6,206)	(6,233)
Receivables—net	$ 390,851	$ 405,378

Revenue from Contracts with C_9

Revenue from Contracts with Customers Contract with Customer, Asset and Liability (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract liabilities	$ 28,830	$ 28,209

Revenue from Contracts with _10

Revenue from Contracts with Customers Revenue, Remaining Performance Obligation (Details) $ in Billions	Mar. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 2.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	9 months
Revenue, Remaining Performance Obligation, Amount	$ 1.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Amount	$ 0.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Amount	$ 0.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Revenue, Remaining Performance Obligation, Amount	$ 0.1

Leases (Narrative) (Details)

Leases (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating lease liability	$ 130,725,000	$ 129,600,000
Operating lease right of use assets	119,807,000	$ 118,700,000	$ 0
Sublease Income	23,000
Short-term Lease, Cost	1,400,000
Variable Lease, Cost	$ 500,000
Minimum [Member]
Lessee Operating And Finance Leases Remaining Lease Term	1 month 6 days
Lessee Operating And Finance Lease, Option to Extend	1 year
Maximum [Member]
Lessee Operating And Finance Leases Remaining Lease Term	11 years
Lessee Operating And Finance Lease, Option to Extend	14 years

Leases Balance Sheet Informatio

Leases Balance Sheet Information (Details) - USD ($)	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Operating Lease [Abstract]
Operating lease right of use assets	$ 119,807,000	$ 118,700,000	$ 0
Operating lease liabilities—current	26,260,000		0
Operating lease liabilities—long term	104,465,000		0
Total operating lease liabilities	130,725,000	$ 129,600,000
Finance Lease [Abstract]
Property and equipment—gross	504,000		$ 0
Accumulated depreciation	(109,000)
Property and equipment—net	395,000
Accounts payable and other accrued expenses	112,000
Other long-term liabilities	293,000
Total finance lease liabilities	$ 405,000

Leases Cost (Details)

Leases Cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease expenses	$ 7,789
Finance Lease, Cost [Abstract]
Depreciation of right of use assets	110
Interest on lease liabilities	9
Finance lease expenses	$ 119

Leases Term and Discount Rate (

Leases Term and Discount Rate (Details)	Mar. 31, 2019
Weighted Average Remaining Lease Term [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	5 years
Finance Lease, Weighted Average Remaining Lease Term	4 years
Weighted Average Discount Rate [Abstract]
Operating Lease, Weighted Average Discount Rate, Percent	4.00%
Finance Lease, Weighted Average Discount Rate, Percent	5.00%

Leases Schedule of Maturity of

Leases Schedule of Maturity of Lease Liabilities (Details)	Mar. 31, 2019USD ($)
Operating Lease Liabilities, Payments, Due [Abstract]
For the nine months ended December 31, 2019	$ 22,331,000
2020	31,704,000
2021	28,610,000
2022	24,941,000
2023	20,661,000
Thereafter	16,404,000
Total future minimum lease payments	144,651,000
Less imputed interest	(13,926,000)
Total	130,725,000
Finance Lease Liabilities, Payments, Due [Abstract]
For the nine months ended December 31, 2019	118,000
2020	135,000
2021	115,000
2022	109,000
2023	12,000
Thereafter	0
Total future minimum lease payments	489,000
Less imputed interest	(84,000)
Total	$ 405,000

Earnings Per Share (Narrative)

Earnings Per Share (Narrative) (Details) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Earnings Per Share [Abstract]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.27	$ 0.25
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	514,224	310,745
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	51,089	203,854	420,524
Stock Issued During Period, Shares, Restricted Stock Vesting	72,188	86,233

Earnings Per Share (Schedule of

Earnings Per Share (Schedule of Earnings Per Share, Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Components of Earnings Per Share, Basic and Diluted [Line Items]
Distributed earnings	$ 10,749	$ 9,867
Undistributed earnings	10,369	10,200
Net income	21,118	20,067
Class A common stock
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders	$ 14,116	$ 13,333
Basic weighted average common shares outstanding	26,584	26,115
Basic earnings per share	$ 0.53	$ 0.51
Diluted net income available to common stockholders	$ 14,157	$ 13,403
Effect of potential exercise of stock options	235	410
Diluted weighted average common shares outstanding	26,819	26,525
Diluted earnings per share	$ 0.53	$ 0.51
Class B common stock
Components of Earnings Per Share, Basic and Diluted [Line Items]
Basic net income available to common stockholders	$ 7,002	$ 6,734
Basic weighted average common shares outstanding	13,188	13,189
Basic earnings per share	$ 0.53	$ 0.51
Diluted net income available to common stockholders	$ 6,961	$ 6,664
Diluted weighted average common shares outstanding	13,188	13,189
Diluted earnings per share	$ 0.53	$ 0.51

Property and Equipment (Propert

Property and Equipment (Property and Equipment) (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Furniture and equipment	$ 105,934,000	$ 97,577,000
Leasehold improvements	43,529,000	43,065,000
Finance leases	504,000	0
Property and equipment—gross	149,967,000	140,642,000
Accumulated depreciation and amortization	(95,488,000)	(89,215,000)
Property and equipment—net	$ 54,479,000	$ 51,427,000

Property and Equipment Narrativ

Property and Equipment Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense related to property and equipment	$ 6.3	$ 5.9

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of Intangible Assets	$ 5.8	$ 7.1

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Goodwill [Roll Forward]
Goodwill at December 31, 2017	$ 1,084,560
Acquisition fair value adjustment	1,246
Goodwill at December 31, 2018	$ 1,085,806

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 407,768	$ 406,857
Accumulated Amortization	240,676	234,895
Net Carrying Amount	167,092	171,962
Contract and program intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	355,932	355,932
Accumulated Amortization	205,977	201,298
Net Carrying Amount	149,955	154,634
Capitalized software cost for internal use
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	51,836	50,925
Accumulated Amortization	34,699	33,597
Net Carrying Amount	$ 17,137	$ 17,328

Goodwill and Other Intangible_6

Goodwill and Other Intangible Assets (Schedule of Other Intangible Assets, Future Amortization Expense) (Details) $ in Thousands	Mar. 31, 2019USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
For the remaining nine months ending December 31, 2019	$ 16,814
For the year ending:
December 31, 2020	21,758
December 31, 2021	19,028
December 31, 2022	16,434
December 31, 2023	13,464
December 31, 2024	$ 12,199

Debt (Revolving Credit Facility

Debt (Revolving Credit Facility) (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 96,000,000	$ 7,500,000
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
Long-term Line of Credit	96,000,000	$ 7,500,000
Line of Credit Facility, Remaining Borrowing Capacity	396,300,000
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
Contingent Liability under Letters of Credit	7,700,000
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 Contingencies_2

Commitments and Contingencies (Letter of Credit) (Narrative) (Details) - Letter of Credit [Member] - Bank of America Syndicate [Member] $ in Thousands	Mar. 31, 2019USD ($)
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 7,700
Performance Guarantee [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 14

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($)	Jan. 02, 2019	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [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	596,422
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		15,148,321
Remaining Aggregate Number of Shares Available For Issuance		6,685,056
Share-based Compensation		$ 1,300,000	$ 1,100,000
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount		0	0
Income tax benefit related to the exercise of stock options and vested cancellations and the vesting of restricted stock		$ 200,000	$ 1,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		5 years	5 years
Expected Annual Cash Dividend		$ 1.08
Granted, Weighted Average Fair Value		$ 10.04	$ 9.96
Share-based Payment Award, Options, Vested, Fair Value		$ 1,200,000	$ 700,000
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not Yet Recognized		$ 7,300,000
Share-based Compensation, Nonvested Awards, Total Compensation Cost Not Yet Recognized, Period for Recognition		2 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		8 years	8 years
Restricted Stock [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		1 year	1 year
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU Performance Factor, Number of Shares Issued		1.5	1.5

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions) (Details)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation [Abstract]
Volatility	26.99%	26.34%
Expected life of options	3 years	3 years
Risk-free interest rate	2.39%	2.46%
Dividend yield	2.00%	2.00%

Stock-Based Compensation (Sch_2

Stock-Based Compensation (Schedule of Share-based Compensation, Stock Options, Activity) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Award, Options, Outstanding [Roll Forward]
Stock options, Number of Shares, Period Start	1,093,400	1,169,408	1,169,408
Granted, Number of Shares	250,231		466,828
Exercised, Number of Shares	(51,089)	(203,854)	(420,524)
Cancelled and expired, Number of Shares	(21,265)		(122,312)
Stock options, Number of Shares, Period End	1,271,277		1,093,400
Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Stock options, Weighted Average Exercise Price, Period Start	$ 45.34	$ 35.88	$ 35.88
Granted, Weighted Average Exercise Price	53.52		54.87
Exercised, Weighted Average Exercise Price	32.61		30.85
Cancelled and expired, Weighted Average Exercise Price	49.48		43.85
Stock options, Weighted Average Exercise Price, Period End	$ 47.39		$ 45.34
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock options outstanding, Aggregate Intrinsic Value	$ 8,846		$ 8,776	$ 16,731
Exercised, Aggregate Intrinsic Value	$ 1,079		$ 12,411
Stock options outstanding, Weighted Average Remaining Contractual Life	4 years
Stock options exercisable, Number of Shares	423,532
Stock options exercisable, Weighted Average Exercise Price	$ 38.93
Stock options exercisable, Aggregate Intrinsic Value	$ 6,392
Stock options exercisable, Weighted Average Remaining Contractual Life	3 years

Stock-Based Compensation (Sch_3

Stock-Based Compensation (Schedule of Non-vested Share Activity) (Details) - $ / shares	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Non-vested [Roll Forward]
Non-vested stock options, Number of Shares, Period Start	774,402
Granted, Number of Shares	250,231		466,828
Vested, Number of Shares	(157,473)
Cancelled, Number of Shares	(19,415)
Non-vested stock options, Number of Shares, Period End	847,745		774,402
Share-based Compensation Arrangement by Share-based Payment Award, Options, Non-vested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested stock options, Weighted Average Fair Value, Period Start	$ 8.77
Granted, Weighted Average Fair Value	10.04	$ 9.96
Vested, Weighted Average Fair Value	7.38
Cancelled, Weighted Average Fair Value	8.95
Non-vested stock options, Weighted Average Fair Value, Period End	$ 9.40		$ 8.77

Stock-Based Compensation (Sch_4

Stock-Based Compensation (Schedule Of Share-based Compensation, Restricted Stock Activity) (Details) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock, Non-vested [Roll Forward]
Non-vested, Period Start | shares	24,000
Granted | shares	24,000
Vested | shares	(28,000)
Non-vested, Period End | shares	20,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Non-vested, Weighted Average Fair Value, Period Start | $ / shares	$ 37.90
Granted, Weighted Average Fair Value | $ / shares	52.83
Vested, Weighted Average Fair Value | $ / shares	40.03
Non-vested, Weighted Average Fair Value, Period End | $ / shares	$ 52.83

Stock-Based Compensation (Sch_5

Stock-Based Compensation (Schedule of Share-based Compensation, Restricted Stock Unit Activity) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Restricted Stock Units, Nonvested, Number of Shares [Roll Forward]
Non-vested, Period Start	137,596	161,343
Granted	88,955	76,713
Vested	(53,688)	(87,200)
Forfeited	(3,267)	(13,260)
Non-vested, Period End	169,596	137,596
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract]
Non-vested, Weighted Average Fair Value, Period Start	$ 45.11	$ 31.36
Granted, Weighted Average Fair Value	51.60	53.97
Vested, Weighted Average Fair Value	40.56	28.40
Forfeited, Weighted Average Fair Value	52.09	38.98
Non-vested, Weighted Average Fair Value, Period End	$ 49.81	$ 45.11

Subsequent Event (Details)

Subsequent Event (Details) $ in Millions	Apr. 01, 2019USD ($)
Subsequent Events [Abstract]
Business Combination, Consideration Transferred	$ 115