ICF International (ICFI) 10-K 28 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 23, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	ICF International, Inc.
Entity Central Index Key	1,362,004
Trading Symbol	ICFI
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		18,620,794
Entity Public Float			$ 855
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents		$ 11,809,000	$ 6,042,000
Contract receivables, net		291,515,000	281,365,000
Prepaid expenses and other		11,327,000	11,724,000
Income tax receivable		5,596,000
Restricted cash - current	[1]	11,191,000
Total Current Assets		331,438,000	299,131,000
Total Property and Equipment, net		38,052,000	40,484,000
Other Assets:
Goodwill		686,108,000	683,683,000
Other intangible assets, net		35,304,000	46,129,000
Restricted cash - non-current		1,266,000	1,843,000
Other assets		18,087,000	14,301,000
Total Assets		1,110,255,000	1,085,571,000
Current Liabilities:
Accounts payable		75,074,000	70,586,000
Accrued salaries and benefits		45,645,000	39,763,000
Accrued expenses and other current liabilities		65,080,000	52,631,000
Deferred revenue		38,571,000	29,394,000
Income tax payable			106,000
Total Current Liabilities		224,370,000	192,480,000
Long-term Liabilities:
Long-term debt		206,250,000	259,389,000
Deferred rent		15,119,000	15,600,000
Deferred income taxes		33,351,000	39,114,000
Other		15,135,000	12,984,000
Total Liabilities		494,225,000	519,567,000
Commitments and Contingencies (Note 17)
Stockholders’ Equity:
Preferred stock, par value $.001 per share; 5,000,000 shares authorized; none issued
Common stock, $.001 par value; 70,000,000 shares authorized; 22,019,315 and 21,663,432 shares issued; and 18,661,801 and 19,021,262 shares outstanding as of December 31, 2017 and December 31, 2016, respectively		22,000	22,000
Additional paid-in capital		307,821,000	292,427,000
Retained earnings		434,766,000	371,890,000
Treasury stock		(121,540,000)	(88,695,000)
Accumulated other comprehensive loss		(5,039,000)	(9,640,000)
Total Stockholders’ Equity		616,030,000	566,004,000
Total Liabilities and Stockholders’ Equity		$ 1,110,255,000	$ 1,085,571,000
[1]	Restricted cash – current for the year ended December 31, 2017 represents amounts held in an escrow account for a future acquisition. See Note 19 – Subsequent Events.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	70,000,000	70,000,000
Common stock, issued (in shares)	22,019,315	21,663,432
Common stock, outstanding (in shares)	18,661,801	19,021,262

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Revenue		$ 1,229,162	$ 1,185,097	$ 1,132,232
Direct costs		771,725	745,137	694,436
Operating costs and expenses
Indirect and selling expenses		346,440	328,048	329,159
Depreciation and amortization		17,691	16,638	16,222
Amortization of intangible assets		10,888	12,481	17,184
Total operating costs and expenses		375,019	357,167	362,565
Operating income		82,418	82,793	75,231
Interest expense		(8,553)	(9,470)	(10,072)
Other income (expense)		121	1,184	(1,559)
Income before income taxes		73,986	74,507	63,600
Provision for income taxes		11,110	27,923	24,231
Net income		$ 62,876	$ 46,584	$ 39,369
Earnings per share:
Basic		$ 3.35	$ 2.45	$ 2.04
Diluted		$ 3.27	$ 2.40	$ 2
Weighted-average common shares outstanding:
Basic		18,766,000	18,989,000	19,335,000
Diluted		19,244,000	19,416,000	19,663,000
Other comprehensive income (loss), net of tax	[1]	$ 4,601	$ (2,149)	$ (5,010)
Comprehensive income, net of tax		$ 67,477	$ 44,435	$ 34,359
[1]	Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2014	$ 500,689		$ 21	$ 267,206	$ 285,937	$ (49,994)	$ (2,481)
Balance (in shares) at Dec. 31, 2014			19,430			1,606
Net income	39,369				39,369
Other comprehensive income (loss)	(5,010)	[1]					(5,010)
Equity compensation	10,850			10,392		$ 458
Exercise of stock options	932			932
Exercise of stock options (in shares)			44
Issuance of shares pursuant to vesting of restricted stock units			234
Net payments for stock issuances and buybacks	(24,861)			276		$ (25,137)
Net payments for stock issuances and buybacks (in shares)			(676)			676
Tax impact of stock option exercises and award vesting	1,307			1,307
Balance at Dec. 31, 2015	523,276		$ 21	280,113	325,306	$ (74,673)	(7,491)
Balance (in shares) at Dec. 31, 2015			19,032			2,282
Net income	46,584				46,584
Other comprehensive income (loss)	(2,149)	[1]					(2,149)
Equity compensation	9,082			8,734		$ 348
Exercise of stock options	3,034		$ 1	3,033
Exercise of stock options (in shares)			128
Issuance of shares pursuant to vesting of restricted stock units			221
Net payments for stock issuances and buybacks	(13,823)			547		$ (14,370)
Net payments for stock issuances and buybacks (in shares)			(360)			360
Balance at Dec. 31, 2016	566,004		$ 22	292,427	371,890	$ (88,695)	(9,640)
Balance (in shares) at Dec. 31, 2016			19,021			2,642
Net income	62,876				62,876
Other comprehensive income (loss)	4,601	[1]					4,601
Equity compensation	10,291			9,985		$ 306
Exercise of stock options	4,722			4,722
Exercise of stock options (in shares)			176
Issuance of shares pursuant to vesting of restricted stock units			180
Net payments for stock issuances and buybacks	(32,464)			687		$ (33,151)
Net payments for stock issuances and buybacks (in shares)			(715)			715
Balance at Dec. 31, 2017	$ 616,030		$ 22	$ 307,821	$ 434,766	$ (121,540)	$ (5,039)
Balance (in shares) at Dec. 31, 2017			18,662			3,357
[1]	Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities
Net income	$ 62,876	$ 46,584	$ 39,369
Adjustments to reconcile net income to net cash provided by operating activities:
Bad debt expense	1,480	1,089	268
Deferred income taxes	(7,390)	6,535	2,106
Non-cash equity compensation	10,291	9,082	10,850
Depreciation and amortization	28,579	29,119	33,406
Deferred rent	(177)	(43)	1,002
Proceeds from hedge sale		3,600
Facilities consolidation reserve	1,479
Amortization of debt issuance costs	673	532	532
Other adjustments, net	275	(1,169)	1,254
Changes in operating assets and liabilities, net of the effect of acquisitions:
Contract receivables	(7,234)	(29,020)	(2,713)
Prepaid expenses and other assets	(1,844)	(2,792)	(170)
Accounts payable	3,631	8,941	(2,374)
Accrued salaries and benefits	5,597	1,140	(13,208)
Accrued expenses and other current liabilities	13,257	10,252	(4,522)
Deferred revenue	8,341	(707)	2,367
Income tax receivable and payable	(5,697)	(2,447)	8,356
Other liabilities	3,054	(639)	(320)
Net Cash Provided by Operating Activities	117,191	80,057	76,203
Cash Flows from Investing Activities
Capital expenditures for property and equipment and capitalized software	(14,513)	(13,791)	(12,682)
Payments for business acquisitions, net of cash received	(91)	(100)	(1,818)
Net Cash Used in Investing Activities	(14,604)	(13,891)	(14,500)
Cash Flows from Financing Activities
Advances from working capital facilities	590,225	478,584	381,745
Payments on working capital facilities	(643,363)	(530,728)	(420,265)
Payments on capital expenditure obligations	(4,808)	(4,041)	(3,289)
Debt issue costs	(1,612)		(17)
Proceeds from exercise of options	4,722	3,034	932
Tax benefits of stock option exercises and award vesting			1,307
Net payments for stockholder issuances and buybacks	(32,464)	(13,823)	(24,861)
Net Cash Used in Financing Activities	(87,300)	(66,974)	(64,448)
Effect of Exchange Rate Changes on Cash, Cash Equivalents, and Restricted Cash	1,094	(416)	(1,746)
Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	16,381	(1,224)	(4,491)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	7,885	9,109	13,600
Cash, Cash Equivalents, and Restricted Cash, End of Period	24,266	7,885	9,109
Supplemental disclosure of cash flow information:
Interest	7,922	8,937	9,845
Income taxes	$ 21,659	$ 21,094	16,315
Non-cash investing and financing transactions:
Capital expenditure obligations			$ 12,870

Basis of Presentation and Natur

Basis of Presentation and Nature of Operations	12 Months Ended
	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation and Nature of Operations	NOTE 1—BASIS OF PRESENTATION AND NATURE OF OPERATIONS Basis of Presentation and Nature of Operations The accompanying consolidated financial statements include the accounts of ICF International, Inc. (“ICFI”) and its subsidiary, ICF Consulting Group, Inc. (“Consulting,” and together with ICFI, “the Company”), and have been prepared in accordance with U.S. generally accepted accounting principles. Consulting is a wholly owned subsidiary of ICFI. ICFI is a holding company with no operations or assets other than its investment in the common stock of Consulting. All other subsidiaries of the Company are wholly owned by Consulting. All significant intercompany transactions and balances have been eliminated. Nature of Operations The Company provides professional services and technology-based solutions to government and commercial clients, including management, technology, and policy consulting and implementation services, in the areas of energy, environment, and infrastructure; health, education, and social programs; safety and security; and consumer and financial. The Company offers a full range of services to these clients throughout the entire life cycle of a policy, program, project, or initiative, from research and analysis and assessment and advice to design and implementation of programs and technology-based solutions, and the provision of engagement services and programs. The Company’s major clients are United States (“U.S.”) federal government departments and agencies, most significantly the Department of Health and Human Services, Department of State and Department of Defense. The Company also serves U.S. state and local government departments and agencies, international governments, and commercial clients worldwide. Commercial clients include airlines, airports, electric and gas utilities, oil companies, banks and other financial services companies, transportation, travel and hospitality firms, non-profits/associations, law firms, manufacturing firms, retail chains, and distribution companies. The term “federal” or “federal government” refers to the U.S. federal government, and “state and local” or “state and local government” refers to U.S. state and local governments, unless otherwise indicated. The Company, incorporated in Delaware, is headquartered in Fairfax, Virginia. It maintains offices throughout the world, including over 59 offices in the U.S. and more than 23 offices in key markets outside the U.S., including offices in the United Kingdom, Belgium, China, India and Canada. Reclassifications Certain immaterial amounts in the 2016 and 2015 consolidated financial statements have been reclassified to conform to the current year presentation. To be consistent with the Company’s current presentation, the Company reclassified $4.3 million of amounts related to deferred compensation liabilities from accrued salaries and benefits to long-term as of December 31, 2016.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 2—SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and contingent liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates. Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, services have been rendered, the contract price is fixed or determinable, and collectability is reasonably assured. The Company enters into three types of contracts: time-and-materials, cost-based, and fixed-price. • Time-and-Materials Contracts. • Cost-Based Contracts . • Fixed-Price Contracts . • Proportional Performance: progress towards completion can be measured based on a reliable output or input. • Specific Performance : hen the services to be performed consist of a single act, revenue is recognized at the time the act is performed or at the completion of the single service. • Straight-Line • Completed Contract Revenue recognition requires the Company to use judgment relative to assessing risks, estimating contract revenue and costs or other variables, and making assumptions for scheduling and technical issues. Due to the size and nature of many of the Company’s contracts, the estimation of revenue and the cost to perform for contracts in process can be complicated and subject to many variables. Contract costs include labor, subcontractor costs, and other direct costs, as well as an allocation of indirect costs. At times, the Company must also make assumptions regarding the length of time to complete the contract because costs include expected increases in wages, prices for subcontractors, and other direct costs. From time to time, the Company obtains new information which causes it to revise its estimated total costs or hours to fulfill contract requirements and thus the associated revenue earned on a contract. To the extent that a revised estimate affects contract profit or revenue previously recognized, the Company records the cumulative effect of the revision in the period in which the facts requiring the revision become known. A provision for the full amount of an anticipated loss on any type of contract is recognized in the period in which the anticipated loss becomes probable and can be reasonably estimated. As a result, operating results could be affected by revisions to prior accounting estimates. Contractual arrangements are evaluated to assess whether revenue should be recognized on a gross versus net basis. Management’s assessment when determining gross versus net revenue recognition is based on several factors, such as whether the Company serves as the primary service provider, has autonomy in selecting subcontractors, or has credit risk, all of which are primary indicators that the Company serves as the principal to the transaction. In such cases, revenue is recognized on a gross basis. When such indicators are not present and the Company is primarily functioning as an agent under an arrangement, revenue is recognized on a net basis, being limited to fees earned for facilitating the transaction. Payments to the Company on cost-based contracts with the U.S. federal government are provisional payments subject to audit and adjustment by the government. Indirect costs applied to government contracts are also subject to audit and adjustment and such audits have been finalized only through December 31, 2007. Contract revenue has been recorded in amounts that are expected to be realized on final audit and settlement of costs. The Company prepares client invoices in accordance with the terms of the applicable contract, and billing terms may not be directly related to the performance of services. Unbilled receivables are invoiced based on the achievement of specific events as defined by each contract, including deliverables, timetables, and incurrence of certain costs. Unbilled receivables are classified as a current asset. Advanced billings to clients in excess of revenue earned are recorded as deferred revenue until the revenue recognition criteria are met. Reimbursements of out-of-pocket expenses are included in revenue when the corresponding costs are included in the cost of revenue. The Company records revenue net of taxes collected from clients when the taxes are to be remitted to governmental authorities. The Company may proceed with work based on client direction prior to the completion and signing of formal contract documents. The Company has a review process for approving any such work. Revenue associated with such work is recognized only when it can be reliably estimated and realization is probable. The Company bases its estimates on a variety of factors, including previous experiences with the client, communications with the client regarding contract status, and its knowledge of the likelihood that contractual limits, or funding, will be increased. Cash and Cash Equivalents The Company considers cash on deposit and all highly liquid investments with original maturities of three months or less when purchased to be cash and cash equivalents. Restricted Cash The Company has restricted cash representing amounts held in escrow accounts and/or not readily available due to contractual restrictions. Allowance for Doubtful Accounts The Company considers a number of factors in its estimate of allowance for doubtful accounts, including the customer’s financial condition, historical collection experience, and other factors that may bear on collectability of the receivables. The Company writes off contract receivables when such amounts are determined to be uncollectible. Property and Equipment Property and equipment are carried at cost and are depreciated using the straight-line method over their estimated useful lives, which range from two to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of the economic life of the improvement or the related lease term. Goodwill and Other Intangible Assets The purchase price of an acquired business is allocated to the tangible assets and separately identifiable intangible assets acquired, less liabilities assumed, based on their respective fair values, with the excess recorded as goodwill. Goodwill represents the excess of costs over the fair value of net assets of businesses acquired. Goodwill and intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized, but instead are reviewed for impairment annually, or more frequently if impairment indicators arise. Intangible assets with estimable useful lives are amortized over such lives and reviewed for impairment if impairment indicators arise. Impairment The Company has historically performed its annual goodwill impairment test as of September 30 of each year. Effective for the annual goodwill impairment test for 2017, the Company performed the required annual test as of October 1. During the fourth quarter of 2017, the Company early adopted the Accounting Standards Update 2017-04, Intangibles—Goodwill and Other (Topic 350) (ASU 2017-04) issued by the Financial Accounting Standards Board (the “FASB”). ASU 2017-04 simplified the calculation and recognition of impairment of goodwill if there is evidence of an impairment based on qualitative or quantitative assessments by eliminating Step 2 of the two step impairment test required by the prior accounting standard. For the purposes of performing the annual goodwill impairment test, the Company has one reporting unit. For the goodwill impairment test as of October 1, 2017, the Company opted to perform a qualitative assessment of whether it is more likely than not that its reporting unit's fair value is less than its carrying amount. If, after completing its qualitative assessment, the Company determines that it is more likely than not that the estimated fair value of the reporting unit exceeded its carrying amount, it may conclude that no impairment exists. If the Company concludes otherwise, a goodwill impairment test must be performed, which includes a comparison of the reporting unit’s fair value to the carrying amount and recognizing as an impairment loss the difference of the reporting unit’s fair value and the carrying amount of goodwill. The Company’s qualitative analysis as of October 1, 2017 included macroeconomic, industry and market specific considerations, financial performance indicators and measurements, and other factors. Based on this qualitative assessment, the Company determined that it is more likely than not that the fair value of its reporting unit exceeded its carrying amount, and thus the impairment test was not required to be performed. Therefore, based on management’s review, a goodwill impairment loss was not required for 2017. Historically, the Company has not recorded any goodwill impairment losses. The Company is required to review long-lived assets and certain identifiable intangibles for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset might not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds its fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less cost to sell. Capitalized Software The Company capitalizes eligible costs to develop enhancements and upgrades to internal-use software that are incurred subsequent to the preliminary project stage. Amortization expense is recorded on a straight-line basis over the expected economic life of the software, typically lasting three to five years. During the years ended December 31, 2017, 2016, and 2015, the costs capitalized for the development of internal-use software were not material to the Company’s consolidated financial statements. Deferred Rent The Company recognizes rent expense on a straight-line basis over the non-cancellable term of each lease, including renewal option periods when renewal is reasonably assured or executed. Lease incentives or abatements received at or near the inception of leases are accrued and amortized ratably over the life of the lease. Stock-based Compensation The Company recognizes stock-based compensation expense related to share-based payments to employees, including grants of employee stock options, restricted stock awards, restricted stock units (“RSUs”), and cash-settled restricted stock units (“CSRSUs”) on a straight-line basis over the requisite service period, which is generally the vesting period. The Company recognizes expense for performance-based share awards (“PSAs”), which have both a performance and condition, on a straight-line basis over the three-year performance period. Non-employee director awards, which do not include vesting conditions, are for board-related services and therefore expensed when earned. Stock-based compensation expense is based on the estimated fair value of the instruments on award and the estimated number of shares the Company ultimately expects will vest. The Company estimates the rate of future forfeitures based on factors such as historical experience and employee class. In addition, the estimation of PSAs that will ultimately vest requires judgment based on the performance and market conditions that will be achieved over the performance period. Changes to these estimates are recorded as a cumulative adjustment in the period estimates are revised. The fair value of stock options, restricted stock awards, RSUs, PSAs, and non-employee director awards is estimated based on the fair value of a share of common stock at the grant date. The Company has elected to use the Black-Scholes-Merton option pricing model to determine the fair value of stock options. The fair value of PSAs is estimated using a Monte Carlo simulation model. CSRSUs are settled only in cash payments. The cash payment is based on the fair value of the Company’s stock price at the vesting date, calculated by multiplying the number of CSRSUs vested by the Company’s closing stock price on the vesting date, subject to a maximum payment cap and a minimum payment floor. The Company treats these awards as liability-classified awards, and, therefore, accounts for them at fair value estimated based on the closing price of the Company’s stock at the reporting date. Other Comprehensive Income (Loss) Other comprehensive income (loss) represents foreign currency translation adjustments arising from the use of differing exchange rates from period to period and the gain on the sale of an interest rate hedge agreement. The financial positions and results of operations of the Company’s foreign subsidiaries are based on the local currency as the functional currency and are translated to U.S. dollars for financial reporting purposes. Assets and liabilities of the subsidiaries are translated at the exchange rate in effect at each balance sheet date. Income statement accounts are translated at the average rate of exchange prevailing during the period. Translation adjustments are reported in accumulated other comprehensive loss included in stockholders’ equity in the Company’s consolidated balance sheets. The activity included in other comprehensive income (loss), net of tax, in the Company’s consolidated statements of comprehensive income for each period reported is summarized below. Year ended December 31, 2017 2016 2015 Foreign currency translation adjustments $ 4,177 $ (4,321 ) $ (5,676 ) Foreign currency realized losses reclassified into earnings — (3 ) 666 Change in fair value of derivative designated as cash flow hedge 441 — — Gain on sale of interest rate hedging agreement, net of tax (1) (17 ) 2,175 — Other comprehensive income (loss), net of tax (2) $ 4,601 $ (2,149 ) $ (5,010 ) ( 1 ) On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge was recorded in other comprehensive income (loss), net of tax, and will be reclassified to earnings when earnings are impacted by the cash flows of the hedged items, the interest payments on the Credit Facility or its replacement from January 31, 2018 to January 31, 2023. See additional details on the hedge agreement in Note 9—Derivative Instruments and Hedging Activities. ( 2 ) Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively. Derivative Instruments Derivative instruments designated as cash flow hedges are recorded on the consolidated balance sheet at fair value as of the reporting date, and the effective portion of the hedge is recorded in other comprehensive income (loss) on the consolidated statement of comprehensive income and reclassified to earnings in the period that the hedged instruments affect earnings. Management reviews the effectiveness of the hedges on a quarterly basis. Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The Company evaluates its ability to benefit from all deferred tax assets and establishes valuation allowances for amounts it believes will more likely than not be unrealizable. For uncertain tax positions, the Company uses a more-likely-than-not recognition threshold based on the technical merits of the income tax position taken. Income tax positions that meet the more-likely-than-not recognition threshold are measured in order to determine the tax benefit recognized in the financial statements. Treasury Shares Treasury shares are accounted for under the cost method. Segment, Customer and Geographic Information The Company operates in one segment based on the consolidated information used by its chief operating decision maker in evaluating the financial performance of its business and allocating resources. This single segment represents the Company’s core business which is providing professional services for government and commercial clients. Although, in order to provide insight into the breadth of its capabilities and diversity of its client base, the Company describes its clients’ four key market areas and evaluates its revenue based on the type of client served, the Company does not manage its business or allocate resources based on those service offerings or types of clients. Approximately $550.3 million, $563.0 million, and $540.0 million of the Company’s revenue for the years 2017, 2016, and 2015, respectively, was derived under prime contracts and subcontracts with agencies and departments of the federal government representing 45%, 48%, and 48% of total revenue, respectively. No other customer accounted for 10% or more of the Company’s revenue during the years ended 2017, 2016, and 2015, respectively. The Company’s international operations provide services to both commercial and international government clients. Revenue is attributed to a particular geographic area based on the administrative location of the client that awarded the contract. The Company’s revenue generated from international clients as a percentage of total revenue was approximately 9%, 10%, and 11% for the years 2017, 2016, and 2015, respectively. At December 31, 2017 and 2016, long-lived assets held internationally were not material. Risks and Uncertainties Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and contract receivables. The majority of the Company’s cash transactions are processed through one U.S. commercial bank. Cash held domestically in excess of daily requirements is used to reduce any amounts outstanding under the Company’s Credit Facility. As of December 31, 2017 and 2016, the Company held approximately $10.4 million and $5.4 million, respectively, of cash in foreign bank accounts. To date, the Company has not incurred losses related to cash and cash equivalents. The Company’s contract receivables consist principally of receivables from agencies and departments of, as well as from prime contractors to, the U.S. federal, state and local, and international governments, as well as from commercial organizations. The Company believes that this respect to federal and other governments, including when the Company is a subcontractor to a prime contractor, The Company has historically been, and continues to be, heavily dependent on contracts with the federal government and is subject to audit, in particular, by agencies of the federal government. Such audits determine, among other things, whether an adjustment of invoices rendered to the government is appropriate under the underlying terms of the contracts. Management does not expect any significant adjustments as a result of government audits that will adversely affect the Company’s financial position. Recent Accounting Pronouncements Recent Accounting Pronouncements Adopted Cash Receipts and Cash Payments In August 2016, FASB issued Accounting Standard Update (“ASU”) 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments that addressed eight specific cash flow issues to reduce the existing diversity in practice. During the third quarter of 2017, the Company elected to early adopt ASU 2016-15, which did not have a material impact on the Company’s consolidated financial statements. Restricted Cash In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force), which requires entities to show the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash and cash equivalents in the statement of cash flows. During the third quarter of 2017, the Company elected to early adopt ASU 2016-18 retrospectively, with adjustments to the 2016 and 2015 fiscal years’ consolidated statements of cash flows. The impact of the adoption on the Company’s previously reported consolidated statements of cash flows is summarized as follows: Year Ended December 31, 2016 Year Ended December 31, 2015 As Reported As Adjusted As Reported As Adjusted Restricted cash $ (494 ) $ — $ 116 $ — Net Cash Provided by Operating Activities 79,563 80,057 76,319 76,203 Effect of exchange rate changes on cash (403 ) (416 ) (1,746 ) (1,746 ) (Decrease) Increase in Cash and Cash Equivalents (1,705 ) — (4,375 ) — Increase in Cash, Cash Equivalents, and Restricted Cash — (1,224 ) — (4,491 ) Cash and Cash Equivalents, Beginning Period 7,747 — 12,122 — Cash, Cash Equivalents, and Restricted Cash, Beginning Period — 9,109 — 13,600 Cash and Cash Equivalents, End of Period 6,042 — 7,747 — Cash, Cash Equivalents, and Restricted Cash, End of Period — 7,885 — 9,109 Goodwill In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350) (ASU 2017-04), which simplifies the measurement of goodwill during the execution of a goodwill impairment test in the event that there is evidence of an impairment based on qualitative or quantitative assessments. ASU 2017-04 does not change how the goodwill impairment is identified, and the Company will continue to perform a qualitative assessment annually to determine whether the two-step impairment test is required. The previous accounting standard required the impairment loss to be recognized under Step 2 of the impairment test. This required the Company to determine whether the carrying amount of the reporting unit’s goodwill exceeds its implied fair value. The implied fair value was calculated by assigning the fair value of the reporting unit to all of its assets and liabilities as if it had been acquired in a business combination. The new standard requires the Company to determine the fair value of the reporting unit and subtract the carrying amount from the fair value of the reporting unit to determine if there is any impairment. If the Company concludes that an impairment exists, an impairment loss will be recorded reflecting the difference of the reporting unit’s estimated fair value over its carrying amount. During the fourth quarter of 2017, the Company elected to early adopt ASU 2017-04, which did not have a material impact on the Company’s consolidated financial statements. Derivative and Hedging In August 2017, the FASB issued ASU 2017-12: Derivatives and Hedging (Topic 815) (ASU 2017-12). ASU 2017-12’s objective is to improve the financial reporting of an entity’s hedges and better aligns an entity’s hedge accounting with the entity’s risk management strategies, as well as simplify the current hedge accounting guidance. During the fourth quarter of 2017, the Company elected to early adopt ASU 2017-12, which did not have a material impact on the Company’s consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted Revenue Recognition In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). ASU 2014-09 provides a single comprehensive revenue recognition framework and supersedes existing revenue recognition guidance. Included in the new principles-based revenue recognition model are changes to the basis for determining the timing for revenue recognition. In addition, the standard expands and improves revenue disclosures. In August 2015, the FASB issued ASU 2015-14 to amend ASU 2014-09 in order to defer the effective date of the new standard. In accordance with this update, the Company elected to adopt the requirements of the new standard effective January 1, 2018. The Company has evaluated the impact of the new guidance on the timing of revenue and expanded disclosure requirements. The Company has concluded that, for the majority of its contracts, there is no material change in the timing of revenue recognition. However, the new standard will result in a change in revenue timing for performance incentives under certain contracts. Under the prior guidance, performance incentives were recognized as revenue when specific quantitative goals were achieved, generally at the end of a measurement period. Under the new standard, these incentives are considered variable consideration and the Company will include in revenue the most likely amount of the priced incentives to be earned as contract work is performed and recognize revenue associated with the incentives over the term of the agreement. This change is not expected to result in a material change to the Company’s annual revenue since most incentives have a one-year measurement period which is aligned with the Company’s fiscal year, but the change may accelerate revenue recognized on a quarterly basis. As of January 1, 2018, the Company adopted the standard using the modified retrospective transition method. Under the modified retrospective method, the new standard applies to new contracts and those that were not completed as of January 1, 2018. For those contracts not completed as of January 1, 2018, the Company is finalizing the catch-up adjustment to retained earnings but does not expect the transition adjustment to be material to the consolidated financial statements. Total net cash provided by operating activities and net cash used by investing and financing activities will not be impacted by the adoption of the new standard. Prior periods will not be retrospectively adjusted, but the Company will maintain dual reporting for the year of initial application in order to disclose the effect on revenue of adopting the new guidance. Additional disclosures under the new standard will, among other required disclosures, disaggregate revenue into categories that reflect how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. Leases In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This update revises an entity’s accounting for operating leases and requires lessees to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. This update also requires that lessees recognize assets and liabilities on the balance sheet for the rights and obligations created by all such leases and requires disclosures designed to give financial statement users information on the amount and timing of lease expenses arising from such leases. These disclosures include certain qualitative and specific quantitative disclosures. For lessees, the new guidance is not expected to significantly change the recognition, measurement, and presentation of expenses arising from a lease. This update is effective for the first interim and annual periods beginning after December 15, 2018, with early adoption permitted. The Company continues to evaluate the impact of adopting ASU 2016-02, the elections to be made at adoption in a modified retrospective approach, the impact of future modifications to the new accounting pronouncement, our inventory of operating leases, the software options that will aid in the implementation and accounting under the new accounting pronouncement, and the timing of adoption. Accumulated other comprehensive In February 2018, the FASB issued ASU 2018-02: Income Statement – Reporting Comprehensive Income (Topic 220) (ASU 2018-02). ASU 2018-02’s objective is to address the application of ASC 740 to certain provisions of the new tax reform legislation commonly known as Tax Cuts and Jobs Act (the “Tax Act”). ASC 740 requires the effect of a change in tax rates on deferred assets and liabilities be included in income from continuing operations in the reporting period that contains the enactment date of the change. The guidance applies even in situations in which the tax effects were initially recognized directly in other comprehensive income at the previous rate, resulting in a stranded amount in accumulated other comprehensive income (loss) (AOCI) related to the income tax rate differential. ASU 2018-02 requires the Company to reclassify the amount of stranded taxes in AOCI to retained earnings. This update is effective for fiscal years beginning after December 15, 2018, including interim periods therein, and early adoption is permitted. The Company is currently evaluating the impact of the pronouncement on the consolidated financial statements.

Contract Receivables

Contract Receivables	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Contract Receivables	NOTE 3—CONTRACT RECEIVABLES Contract receivables, net of the established allowance, are stated at amounts expected to be realized in future periods. Unbilled receivables result from revenue that has been earned but cannot be billed yet under the terms of the contract. Unbilled receivables can be invoiced at contractually defined intervals or milestones, as well as on completion of the contract or government audits. The Company anticipates that the majority of unbilled receivables will be substantially billed and collected within one year, and therefore, classifies them as current assets in accordance with industry practice. Contract receivables consisted of the following at December 31: 2017 2016 Billed $ 169,027 $ 168,012 Unbilled 117,037 108,432 Retainages 6,160 5,088 Other 3,144 2,424 Allowance for doubtful accounts (3,853 ) (2,591 ) Contract receivables, net $ 291,515 $ 281,365

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property and Equipment	NOTE 4—PROPERTY AND EQUIPMENT Property and equipment consisted of the following at December 31: 2017 2016 Leasehold improvements $ 18,873 $ 17,847 Software 42,835 41,269 Furniture and equipment 26,076 26,570 Computers 28,826 28,874 116,610 114,560 Accumulated depreciation and amortization (78,558 ) (74,076 ) Total property and equipment, net $ 38,052 $ 40,484 Depreciation and amortization expense for the years ended December 31, 2017, 2016, and 2015, was approximately $17.7 million, $16.6 million, and $16.2 million, respectively.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	NOTE 5—GOODWILL AND OTHER INTANGIBLE ASSETS Goodwill The changes in the carrying amount of goodwill for the fiscal years ended December 31 were as follows: 2017 2016 Balance as of January 1 $ 683,683 $ 687,404 Goodwill resulting from the Trade NTE business combination — 191 Goodwill resulting from the Mostra business combination — 654 Goodwill resulting from the Olson business combination — 267 Effect of foreign currency translation 2,425 (4,833 ) Total goodwill $ 686,108 $ 683,683 Other Intangible Assets Intangible assets with definite lives are primarily amortized over periods ranging from approximately 4 to 10 years. The weighted-average period of amortization for all intangible assets as of December 31, 2017 is 9.1 years. The customer-related intangible assets, which consist of customer contracts, backlog, and non-contractual customer relationships, are being amortized based on estimated cash flows and respective estimated economic benefit of the assets. The weighted-average period of amortization of the customer-related intangibles is 9.1 years. Intangible assets related to developed technology are being amortized on an accelerated basis over a weighted-average period of 5.5 years. Intangible assets with an indefinite life consist of a domain name. Other intangibles consisted of the following at December 31: 2017 Gross Carrying Value Accumulated Amortization Net Carrying Value Customer-related $ 84,878 $ (49,782 ) $ 35,096 Developed technology 1,463 (1,350 ) 113 Total amortizable intangible assets 86,341 (51,132 ) 35,209 Intangible with indefinite life 95 — 95 Total other intangible assets $ 86,436 $ (51,132 ) $ 35,304 2016 Gross Carrying Value Accumulated Amortization Net Carrying Value Customer-related $ 115,806 $ (70,090 ) $ 45,716 Developed technology 1,463 (1,145 ) 318 Total amortizable intangible assets 117,269 (71,235 ) 46,034 Intangible with indefinite life 95 — 95 Total other intangible assets $ 117,364 $ (71,235 ) $ 46,129 Aggregate amortization expense for the years ended December 31, 2017, 2016, and 2015, was approximately $10.9 million, $12.5 million, and $17.2 million, respectively. The estimated future amortization expense relating to intangible assets is as follows: Year ending December 31, 2018 $ 8,441 2019 6,132 2020 4,532 2021 4,082 2022 4,125 Thereafter 7,897 Total $ 35,209

Accrued Salaries and Benefits

Accrued Salaries and Benefits	12 Months Ended
	Dec. 31, 2017
Employee Related Liabilities Current [Abstract]
Accrued Salaries and Benefits	NOTE 6—ACCRUED SALARIES AND BENEFITS Accrued salaries and benefits consisted of the following at December 31: 2017 2016 Accrued paid time off and leave $ 11,904 $ 11,342 Accrued salaries 9,343 9,443 Accrued bonuses, liability-classified awards and commissions 16,909 13,025 Accrued payroll taxes and withholdings 2,557 1,948 Accrued medical 3,720 3,026 Other 1,212 979 Total accrued salaries and benefits $ 45,645 $ 39,763

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	NOTE 7—ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES Accrued expenses and other current liabilities consisted of the following at December 31: 2017 2016 Accrued subcontractor and other direct costs $ 47,508 $ 30,153 Deposits 6,641 12,389 Accrued IT and software licensing costs 2,261 5,349 Accrued taxes and insurance premiums 1,963 1,306 Accrued lease exit and facilities costs 1,591 77 Accrued interest 705 841 Accrued professional services 1,131 795 Other accrued expenses and current liabilities 3,280 1,721 Total accrued expenses and other current liabilities $ 65,080 $ 52,631

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt	NOTE 8—LONG-TERM DEBT On May 17, 2017, the Company entered into a Fifth Amended and Restated Business Loan and Security Agreement with a syndication of 11 commercial banks (the “Credit Facility”). The Credit Facility: (i) includes modifications to the Company’s Fourth Amended and Restated Business Loan and Security Agreement, (ii) matures on May 17, 2022, (iii) increases the borrowing ceiling up to $600.0 million without a borrowing base requirement, taking into account financial, performance-based limitations, and (iv) provides for an “accordion,” which permits additional revolving credit commitments of up to $300.0 million, subject to lenders’ approval. While the modification of the Credit Facility did not increase the amount of outstanding, $106.0 million of funds from new syndicated borrowings was used to pay off or pay down borrowings from syndicate members prior to the loan modification and align the allocation of debt within the syndicate. These amounts were included within the “Advances from working capital facilities” and “Payments on working capital facilities” line items in the statement of cash flows for the year ended December 31, 2017. The Company has the option to borrow funds under the Credit Facility at interest rates based on both LIBOR (1, 3, or 6 month rates) and the Base Rate, at its discretion, plus their applicable margins. Base Rates are fluctuating per annum rates of interest equal to the highest of (i) the Federal Funds Open Rate, plus 0.5%, (ii) the Prime Rate, and (iii) the daily LIBOR rate, plus a LIBOR Margin of between 1.00% and 2.00% based on our Leverage Ratio (as defined under the Credit Facility), 1.25% as of December 31, 2017. The interest accrued based on LIBOR rates is to be paid on the last business day of the interest period (1, 3, or 6 months), while interest accrued based on the Base Rates is to be paid in quarterly installments. The Credit Facility provides for letters of credit aggregating up to $60.0 million which reduce the funds available under the Credit Facility when issued. The Credit Facility is collateralized by substantially all of the assets of the Company and requires that the Company remain in compliance with certain financial and non-financial covenants. The financial covenants require, among other things, that the Company maintain at all times an Interest Coverage Ratio (as defined under the Credit Facility) of not less than 3.00 to 1.00 and a Leverage Ratio of not more than 3.75 to 1.00 (subject to adjustment, in certain circumstances) for each fiscal quarter. As of December 31, 2017, the Company was in compliance with its covenants under the Credit Facility. The Credit Facility was subject to a commitment fee on the unused portion of the Credit Facility of between 0.13% and 0.25% per annum, based on our Leverage Ratio, 0.15% per annum at December 31, 2017 and 0.25% per annum at December 31, 2016. As of December 31, 2017, the available borrowing capacity under the Credit Facility (excluding the accordion) was $390.0 million. Taking into account the financial and performance-based limitations, the available borrowing capacity (excluding the accordion) was $245.1 million as of December 31, 2017. Long-term debt outstanding and the weighted average interest rate at December 31 is summarized as follows: 2017 2016 Debt Outstanding Weighted Average Interest Rate Debt Outstanding Weighted Average Interest Rate Revolving Line of Credit/Swing Line $ 206,250 2.65 % $ 259,389 2.46 % Debt Issuance Cost The Company’s debt issuance costs, which are included within other assets, are amortized over the term of indebtedness. Amortizable debt issuance costs were $6.9 million and $5.8 million as of December 31, 2017 and 2016, respectively. Accumulated amortization related to debt issuance costs were $4.7 million and $4.5 million, as of December 31, 2017 and 2016, respectively. Amortization expense of $0.7 million, $0.5 million, and $0.5 million was recorded for each of the years ended December 31, 2017, 2016, and 2015, respectively. The Company incurred $1.6 million in debt issuance costs for the year ended December 31, 2017. Letters of Credit At December 31, 2017 and 2016, the Company had twelve and nine outstanding letters of credit totaling approximately $3.7 million and $3.4 million, respectively. These letters of credit are renewed annually.

Derivative instruments and Hedg

Derivative instruments and Hedges Activities	12 Months Ended
	Dec. 31, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative instruments and Hedges Activities	NOTE 9—DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES On August 31, 2017, the Company entered into a floating-to-fixed interest rate swap agreement for an aggregate notional amount of $25.0 million which hedged a portion of the Company’s floating rate indebtedness. The swap agreement requires the Company to pay a fixed rate of 1.8475% per annum plus the applicable margin pursuant to the Credit Facility. Notwithstanding the terms of the interest rate swap transaction, the Company is ultimately obligated for all amounts due and payable under the Credit Facility. The cash flows from the transaction begin August 31, 2018 and end on August 31, 2023. The Company has designated the swap as a cash flow hedge. On a quarterly basis, management evaluates the swap to determine its effectiveness or ineffectiveness. Management intends that the swap remain effective. Realized gains and losses in connection with each required interest payment will be reclassified from AOCI to interest expense. On September 30, 2016, the Company entered into a floating-to-fixed interest rate hedge agreement for an aggregate notional amount of $100.0 million which hedged a portion of the Company’s floating rate indebtedness. The cash flows from the interest rate swap agreement begin on January 31, 2018 and end on January 31, 2023. The Company designated the swap as a cash flow hedge. On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge, as of the date of the sale, was recorded in other comprehensive income, net of tax. The gain from the sale will be recognized into earnings when earnings are impacted by the cash flows of the previously hedged items, as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023. As of December 31, 2017, the net amount of realized gains and losses from the hedge agreements expected to be reclassified from AOCI into earnings within the next 12 months is $0.7 million. The Company uses interest rate swap arrangements to manage or hedge its interest rate risk. The Company does not use such instruments for speculative or trading purposes.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 10—INCOME TAXES The domestic and foreign components of income before provision for income taxes are as follows for the years ended December 31: 2017 2016 2015 Domestic $ 69,347 $ 69,159 $ 54,150 Foreign 4,639 5,348 9,450 Income before income taxes $ 73,986 $ 74,507 $ 63,600 Income tax expense consisted of the following for the years ended December 31: 2017 2016 2015 Current: Federal $ 12,995 $ 12,979 $ 14,797 State 3,243 3,514 2,669 Foreign 1,476 1,932 1,475 Total current 17,714 18,425 18,941 Deferred: Federal (9,425 ) 8,872 4,562 State 2,749 1,222 512 Foreign 72 (596 ) 216 Total deferred (6,604 ) 9,498 5,290 Income tax expense $ 11,110 $ 27,923 $ 24,231 Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and income tax purposes. Deferred tax assets (liabilities) consisted of the following at December 31: 2017 2016 Deferred Tax Assets Allowance for bad debt $ 1,003 $ 1,008 Accrued paid time off 1,624 2,592 Accrued bonus — 55 Foreign net operating loss (NOL) carry forward 1,301 1,371 Federal/state net operating loss (NOL) carry forward 507 3,010 Stock option compensation 2,726 4,292 Deferred rent 3,355 5,423 Deferred compensation 3,238 3,662 Foreign tax credits 505 2,631 State tax credits 1,785 1,784 Federal tax credits — 225 Foreign exchange 2,051 5,349 Accrued liabilities and other 3,272 3,378 21,367 34,780 Less: Valuation Allowance (1,636 ) (1,131 ) Total Deferred Tax Assets 19,731 33,649 Deferred Tax Liabilities Retention (1,375 ) (1,684 ) Prepaid expenses (1,045 ) (1,654 ) Payroll taxes (489 ) (617 ) Unbilled revenue (5,407 ) (8,728 ) Depreciation (4,773 ) (6,664 ) Amortization (39,993 ) (51,842 ) Deferred gain and other — (1,574 ) Total Deferred Tax Liabilities (53,082 ) (72,763 ) Total Net Deferred Tax Liability $ (33,351 ) $ (39,114 ) On December 20, 2017, the U.S. Congress passed the “Tax Cuts and Jobs Act” (the “Tax Act”), which was signed into law on December 22, 2017 and is generally effective beginning January 1, 2018. The Company will be impacted in several ways as a result of the Tax Act, including, but not limited to, provisions which include a permanent reduction in the U.S. federal corporate income tax rate from 35% to 21%, the revaluation of deferred tax assets and liabilities required as a result of the tax rate change and the application of a mandatory one-time “transition tax” on unremitted earnings of certain foreign subsidiaries that were previously tax deferred. The Company has not completed the accounting for the tax effects of enactment of the Tax Act; however, in certain cases, as described below, the Company has made a provisional estimate of the effects on our existing deferred tax balances and the one-time transition tax. The Company has recognized the provisional estimate as a reduction in the provision for income taxes, which is included as a component of income tax expense from continuing operations. The Company re-measured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. However, the Company is still analyzing certain aspects of the Tax Act and refining estimates, which could potentially affect the measurement of these balances or potentially give rise to new deferred tax amounts. Pursuant to SAB 118, the provisional amount recorded related to the re-measurement of the deferred tax balances was a net tax benefit of $17.6 million. The one-time “transition tax” is based on the Company’s total post-1986 earnings and profits (E&P) which the Company has previously deferred from US income taxation. Pursuant to SAB 118, the Company recorded a provisional estimate of approximately $1.4 million, net of related foreign tax credits, for the one-time transition tax liability for the Company’s foreign subsidiaries, resulting in an increase in income tax expense. The Company has not yet completed the calculation of the total post-1986 foreign E&P and related foreign tax pools for these foreign subsidiaries. Further, the transition tax is based in part on the amount of those earnings held in cash and other specified assets. This amount, as well as the related foreign tax credit utilization, may change when the Company finalizes the calculation of post-1986 foreign E&P and related foreign tax pools that were previously deferred from US federal taxation and once the Company finalizes the amounts held in cash or other specified assets. Similarly, our cumulative foreign tax credit carry forward balance as of December 31, 2017 and any valuation allowance required (as applicable) may also change. No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax and any additional outside basis difference inherent in these entities as these amounts continue to be permanently reinvested in foreign operations. The impact of the transition tax is a preliminary estimate and will not be finalized until the later part of 2018. At both December 31, 2017 and 2016 At December 31, 2017 Section At December 31, 2017, the Company had gross state income tax credit carry-forwards of approximately $2.8 million, which expire between 2017 and 2026. A deferred tax asset of approximately $1.8 million (net of federal benefit) has been established related to these state income tax credit carry-forwards as of December 31, 2017. The need to establish valuation allowances for deferred assets is based on a more-likely-than-not threshold that the benefit of such assets will be realized in future periods. Appropriate consideration has been given to all available evidence, including historical operating results, projections of taxable income, and tax planning alternatives. The Company concluded that a valuation allowance of approximately $1.1 million and $1.1 million was required for tax attributes related to specified foreign jurisdictions as of December 31, 2017 and 2016, respectively, and an additional $0.5 million valuation allowance was recorded against our US foreign tax credit carry forwards as a result of enactment of the Tax Act as of December 31, 2017. Due to the interplay of the “transition tax” referenced above and the utilization of foreign tax credits, the amount of valuation allowance recorded against our US foreign tax credit carry forwards as of December 31, 2017 is subject to change once the Company finalizes its calculations. The total amount of unrecognized tax benefits as of December 31, 2017 and 2016, was $0.8 million and $1.2 million, respectively. Included in the balance as of December 31, 2017 and 2016, were $0.7 million and $1.0 million, respectively, of tax positions that, if recognized, would impact the effective tax rate. The unrecognized tax benefit reconciliation, excluding penalty and interest, is as follows: Unrecognized tax benefits at January 1, 2015 $ 702 Decrease attributable to settlements (174 ) Increase attributable to tax positions taken during a prior period 12 Decrease attributable to lapse of statute of limitations (140 ) Unrecognized tax benefits at December 31, 2015 400 Increase attributable to tax positions taken during a prior period 925 Decrease attributable to lapse of statute of limitations (140 ) Unrecognized tax benefits at December 31, 2016 1,185 Decrease attributable to lapse of statute of limitations (365 ) Unrecognized tax benefits at December 31, 2017 $ 820 The Company’s policy is not to recognize accrued interest and penalties related to unrecognized tax benefits as a component of tax expense. The Company had approximately $0.2 million and $0.2 million of accrued penalty and interest at December 31, 2017 and 2016, respectively. The Company’s 2013 to 2016 tax years remain subject to examination by the Internal Revenue Service for federal tax purposes. Certain significant state and foreign tax jurisdictions are also either currently under examination or remain open under the statutes of limitation and subject to examination for the tax years from 2013 to 2016. Although the Company believes it has adequately provided for all uncertain tax positions, amounts asserted by taxing authorities could be greater than the Company’s accrued position. Accordingly, additional provisions on federal, state and foreign income tax related matters could be recorded in the future as revised estimates are made or the underlying matters are effectively settled or otherwise resolved. Conversely, the Company could settle positions with the tax authorities for amounts lower than have been accrued. The Company believes it is reasonably possible that, during the next 12 months, the Company’s liability for uncertain tax positions may decrease by approximately $0.7 million. The Company’s provision for income taxes differs from the federal statutory rate. The differences between the statutory rate and the Company’s provision are as follows: 2017 2016 2015 Taxes at statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 4.4 % 3.9 % 3.9 % Foreign tax rate differential (0.3 )% (0.1 )% (0.3 )% Tax legislation (22.6 )% — — Other permanent differences 0.7 % 0.8 % 1.9 % Prior year tax adjustments (0.3 )% (1.0 )% (1.9 )% Unrecognized tax benefits 0.1 % 1.0 % — Valuation allowance 0.7 % (0.3 )% — Equity-based compensation (2.1 )% (1.0 )% — Tax credits (0.6 )% (0.8 )% (0.5 )% Taxes at effective rate 15.0 % 37.5 % 38.1 %

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Accumulated Other Comprehensive Loss	NOTE 11—ACCUMULATED OTHER COMPREHENSIVE LOSS As of December 31, 2017 and 2016, accumulated other comprehensive loss, net of tax, included the following: 2017 2016 Foreign currency translation adjustments $ 7,638 $ 11,815 Gain on sale of interest rate hedge agreement (1) (2,158 ) (2,175 ) Change in fair value on derivative designated as cash flow hedge (2) (441 ) — Total $ 5,039 $ 9,640 (1) Represents the fair value of an interest rate hedge agreement, designated as a cash flow hedge, which was sold on December 1, 2016. The fair value of the interest rate hedge agreement was recorded in other comprehensive income, net of tax, and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities. (2) Represents the change in fair value of an interest rate hedge agreement designated as a cash flow hedge, and entered into on August 31, 2017. The fair value of the interest rate hedge agreement was recorded in other comprehensive income and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from August 31, 2018 to August 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2017
Cash And Cash Equivalents [Abstract]
Restricted Cash	NOTE 12 — The following table provides a reconciliation of cash and cash equivalents, and restricted cash reported within the consolidated balance sheets at December 31, 2017 and 2016 to the total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows for the years ended December 31, 2017, 2016, and 2015: 2017 2016 2015 Beginning Ending Beginning Ending Beginning Ending Cash and cash equivalents $ 6,042 $ 11,809 $ 7,747 $ 6,042 $ 12,122 $ 7,747 Restricted cash - current (1) — 11,191 — — — — Restricted cash - non-current 1,843 1,266 1,362 1,843 1,478 1,362 Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows $ 7,885 $ 24,266 $ 9,109 $ 7,885 $ 13,600 $ 9,109 (1) Restricted cash – current for the year ended December 31, 2017 represents amounts held in an escrow account for a future acquisition. See Note 19 – Subsequent Events.

Accounting for Stock-based Comp

Accounting for Stock-based Compensation	12 Months Ended
	Dec. 31, 2017
Accounting For Stock Based Compensation [Abstract]
Accounting for Stock-based Compensation	NOTE 13—ACCOUNTING FOR STOCK-BASED COMPENSATION Stock Incentive Plans On June 5, 2015, the Company’s stockholders approved an amendment (the “Amendment”) to the ICF International, Inc. 2010 Omnibus Incentive Plan (as amended, the “Omnibus Plan”). The Amendment, among other items, increased the new shares available for issuance under the Omnibus Plan by 1,540,000 shares from 3,550,000 to 5,090,000 (for an aggregate 5,966,186 shares, which includes shares that remained available under the 2006 Long-Term Equity Incentive Plan when the Omnibus Plan was initially adopted). The Omnibus Plan provides for the granting of options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, cash-based awards, and other stock-based awards to all officers, key employees, and non-employee directors of the Company. Under the terms of the Omnibus Plan, shares awarded that are not stock options or stock appreciation rights, are counted as 1.93 shares deducted for every one share delivered under those awards. Shares awarded that are stock options or stock appreciation rights are counted as a single share deducted from the Omnibus Plan for every one share delivered under those awards. As of December 31, 2017, the Company had approximately 1.9 million shares available to grant under the Amended Plan. CSRSUs have no impact on the shares available for grant under the Omnibus Plan, and have no impact on the calculated shares used in earnings per share calculations. The total stock-based compensation expense for the years ended December 31, 2017, 2016, and 2015, the unrecognized compensation expense at December 31, 2017, and the weighted-average period to recognize the remaining unrecognized shares are as follows: Stock-Based Compensation Expense Recognized as of December 31, Unrecognized 2017 2016 2015 December 31, 2017 Weighted-Average Period to Recognize (years) Stock Options $ 164 $ 909 $ 1,546 $ — — Restricted Stock Units 7,080 6,325 7,409 12,659 1.9 Cash-Settled Restricted Stock Units 7,253 7,091 4,414 13,922 1.9 Non-Employee Director Awards 671 741 645 — — Performance Shares 2,376 877 727 2,717 1.5 Total $ 17,544 $ 15,943 $ 14,741 $ 29,298 The assumptions of employment termination forfeiture rates used in the determination of fair value of stock awards during the 2017 calendar year were based on the Company’s historical average of actual forfeitures from the previous 5 years preceding the reporting period. The expected annualized forfeiture rates used during the 2017 calendar year varied from 1.86% to 19.51%, and the Company does not expect these termination rates to vary significantly in the future. Stock Options Option awards are granted with an exercise price equal to the market value of the Company’s common stock on the date of grant. All options outstanding as of December 31, 2017 have a 10-year contractual term. Options generally have a vesting term of three or four years. There were no option awards granted during 2017, 2016, and 2015. The following table summarizes the changes in outstanding stock options: Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Outstanding at January 1, 2015 766,924 $ 28.20 Exercised (43,919 ) $ 21.23 Granted — $ — Forfeited/Expired — $ — Outstanding at December 31, 2015 723,005 $ 28.62 Exercised (128,301 ) $ 23.65 Granted — $ — Forfeited/Expired (7,297 ) $ 40.68 Outstanding at December 31, 2016 587,407 $ 29.56 Exercised (175,909 ) $ 26.84 Granted — $ — Forfeited/Expired — $ — Outstanding at December 31, 2017 411,498 $ 30.71 $ 8,965 Vested plus expected to vest at December 31, 2017 411,498 $ 30.71 $ 8,965 Exercisable at December 31, 2017 411,498 $ 30.71 $ 8,965 The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $52.50 as of December 31, 2017. The total intrinsic value of options exercised was $4.5 million, $2.5 million, and $0.8 million for the years ended December 31, 2017, 2016, and 2015, respectively. The fair value of shares vested was $1.9 million, $1.3 million, and $2.0 million for the years ended December 31, 2017, 2016, and 2015, respectively. As of December 31, 2017, the weighted-average remaining contractual term for options vested was 5.0 years and for exercisable options was 5.0 years. Information regarding stock options outstanding as of December 31, 2017 is summarized below: OPTIONS OUTSTANDING OPTIONS EXERCISABLE Range of Exercise Prices Number Outstanding As of December 31, 2017 Weighted Average Remaining Contractual Term Weighted Average Exercise Price Number Exercisable As of December 31, 2017 Weighted Average Exercise Price $21.77 to $25.00 62,917 3.3 $ 21.77 62,917 $ 21.77 $25.01 to $28.00 205,332 4.8 $ 26.50 205,332 $ 26.50 $28.01 to $40.68 143,249 6.1 $ 40.68 143,249 $ 40.68 $21.77 to $41.00 411,498 5.0 $ 30.71 411,498 $ 30.71 Restricted Stock Units RSUs generally have a vesting term of three or four years. On vesting the employee is issued one share of stock for each RSU awarded. The fair value of shares vested was $6.3 million , A summary of the Company’s RSUs is presented below. Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested RSUs at January 1, 2015 643,887 $ 31.10 Granted 250,159 $ 39.04 Vested (233,899 ) $ 26.85 Cancelled (104,243 ) $ 36.76 Non-vested RSUs at December 31, 2015 555,904 $ 35.40 Granted 240,868 $ 34.68 Vested (221,659 ) $ 32.45 Cancelled (67,115 ) $ 37.60 Non-vested RSUs at December 31, 2016 507,998 $ 36.12 Granted 194,227 $ 41.41 Vested (179,974 ) $ 35.19 Cancelled (58,664 ) $ 36.04 Non-vested RSUs at December 31, 2017 463,587 $ 38.71 $ 24,338 RSUs expected to vest in the future 463,587 $ 38.71 $ 24,338 The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $52.50 per share as of December 31, 2017. Cash-Settled Restricted Stock Units CSRSUs generally have a vesting term of four years. A summary of the Company’s CSRSUs is presented below. Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested CSRSUs at January 1, 2015 537,119 $ 36.36 Granted 121,015 $ 39.35 Vested (78,033 ) $ 33.29 Cancelled (133,438 ) $ 38.14 Non-vested CSRSUs at December 31, 2015 446,663 $ 37.18 Granted 233,790 $ 34.29 Vested (146,619 ) $ 34.70 Cancelled (70,812 ) $ 37.55 Non-vested CSRSUs at December 31, 2016 463,022 $ 35.96 Granted 174,419 $ 42.06 Vested (161,576 ) $ 40.78 Cancelled (83,949 ) $ 36.43 Non-vested CSRSUs at December 31, 2017 391,916 $ 38.80 $ 20,576 CSRSUs expected to vest in the future 391,916 $ 38.80 $ 20,576 The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $52.50 per share as of December 31, 2017. The fair value of CSRSUs vested and settled in cash for the years ended December 31, 2017, 2016, and 2015 was $6.9 million, $5.9 million and $2.9 million, respectively. Non-Employee Director Awards The Company grants awards of unregistered shares to its non-employee directors on a quarterly basis under its Annual Equity Election. The awards are issued from the Company’s treasury stock and have no impact on the shares available for grant under the Omnibus Plan. Non-employee director awards do not include vesting conditions; thus, there was no unrecognized expense related to these awards at December 31, 2017. A summary of the Company’s non-employee director awards granted by fiscal year is presented below. For the Year ended December 31, Number of shares Granted Weighted- Average Grant Date Fair Value 2015 18,109 $ 35.62 2016 15,299 $ 39.32 2017 13,861 $ 48.41 Performance Share Awards In the first quarter of 2015, the Company’s Board of Directors approved a performance-based share program (the “Program”) that provides for the issuance of PSAs to its senior management. Under the Program, the number of PSAs that the participant will receive depends on the Company’s achievement of two performance goals during two performance periods. The performance goals under the Program are based on (i) the Company’s compounded annual growth rate in earnings per share (“EPS”) during a two-year performance period and (ii) the Company’s cumulative total shareholder return (“rTSR”) relative to its peer group during a performance period from the first day of the performance period (typically January 1 of the year awarded) to the last day of the third year of the performance period (typically December 31). The PSAs will only be eligible to vest only following the expiration of the three-year performance period. Actual shares vested will be subject to both continued employment by the Company (barring certain exceptions allowing for partial performance periods) and actual financial measures achieved. The actual number of shares of common stock that will be issued to each participant at the end of the applicable performance period will be determined by multiplying the award by the product of two percentages, one based on the Company’s EPS performance and a second one based on the Company’s rTSR performance, subject to a minimum and maximum performance level. As of December 31, 2017, shares granted during 2015, 2016, and 2017 are within year three, two, and one of the performance period, respectively, and therefore have not vested. A summary of the Company’s PSAs is presented below. Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested PSAs at January 1, 2015 — $ — Granted 58,822 $ 44.21 Vested — $ — Cancelled — $ — Non-vested PSAs at December 31, 2015 58,822 $ 44.21 Granted 74,574 $ 37.75 Vested — $ — Cancelled (3,422 ) $ 41.61 Non-vested PSAs at December 31, 2016 129,974 $ 40.57 Granted 60,929 $ 38.81 Vested — $ — Cancelled (3,881 ) $ 42.83 Non-vested PSAs at December 31, 2017 187,022 $ 39.95 $ 9,819 PSAs expected to vest in the future 126,846 $ 38.09 $ 6,659 The aggregate intrinsic value in the preceding table is based on the Company’s closing stock price of $52.50 per share as of December 31, 2017. The fair value of the awards is estimated on the grant date using a Monte Carlo simulation model due to the market condition for the rTSR component. The fair value assumptions using the Monte Carlo simulation model for awards granted in 2017, 2016, and 2015 were 0.0% for dividend yields; 31.3%, 30.9% and 29.3% for historical volatility, respectively; and 1.5%, 1.0%, and 1.0% both risk-free rate of returns, respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	NOTE 14—EARNINGS PER SHARE EPS is computed by dividing reported net income by the weighted-average number of shares outstanding. Diluted EPS considers the potential dilution that could occur if common stock equivalents of stock options, RSUs, and PSAs were exercised or converted into stock. PSAs are included in the computation of diluted shares only to the extent that the underlying performance conditions (i) are satisfied as of the end of the reporting period or (ii) would be considered satisfied if the end of the reporting period were the end of the related performance period and the result would be dilutive under the treasury stock method. For the years ended December 31, 2017, 2016, and 2015, there were 142, 163,564 and 167,849, respectively, weighted-average shares excluded from the calculation of EPS because they were anti-dilutive. The dilutive effect of stock options, RSUs, and performance shares for each period reported is summarized below: (in thousands) 2017 2016 2015 Basic weighted-average shares outstanding 18,766 18,989 19,335 Effect of potential exercise of stock options, RSUs, and performance shares 478 427 328 Diluted weighted-average shares outstanding 19,244 19,416 19,663

Share Repurchase Program

Share Repurchase Program	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Share Repurchase Program	NOTE 15—SHARE REPURCHASE PROGRAM In the third quarter of 2015, the Company’s board of directors approved the share repurchase plan effective in November 2015 that extended the share repurchase plan through November 2017 and authorized share repurchases in the aggregate up to $75.0 million, not to exceed limits under the Credit Facility. As part of the Company’s modification of the Credit Facility, the prior Credit Facility limits on share repurchases were eliminated to permit unlimited share repurchases, provided the Company’s Leverage Ratio, prior to and after giving effect to such repurchases, is not greater than 3.25 to 1.00. During September 2017, the board of directors approved a new repurchase program and repurchase plan effective November 4, 2017 through November 4, 2019 with a limit of $100.0 million. The limitation under the Credit Facility remains unchanged. Purchases under this program may be made from time to time at prevailing market prices in open market purchases or in privately negotiated transactions pursuant to Rules 10b5-1 and 10b-18 under the Exchange Act and in accordance with applicable insider trading and other securities laws and regulations. The purchases are funded from existing cash balances and/or borrowings, and the repurchased shares are held in treasury and used for general corporate purposes. The timing and extent to which the Company repurchases its shares will depend on market conditions and other corporate considerations at the Company’s sole discretion. During the year ended December 31, 2017, the Company repurchased 684,335 shares at a total cost of $30.7 million under this program. As of December 31, 2017, approximately $100.0 million remained available under the share repurchase plan.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value	NOTE 16—FAIR VALUE The Company measures and reports certain financial assets and liabilities at fair value in accordance with ASC 820, Fair Value Measurements and Disclosures (“ASC 820”). Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants on the measurement date. Generally, fair value is based on observable quoted market prices or derived from observable market data when such market prices or data are available. ASC 820 establishes a three-level hierarchy used to estimate fair value by which each level is categorized based on the priority of the inputs used to measure fair value: • Level 1: Quoted prices that are available in active markets for identical assets or liabilities; • Level 2: Quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active; inputs other than quoted prices that are observable for the asset or liability (e.g., interest rates and yield curves that are observable at commonly quoted intervals, and implied volatilities); and inputs derived principally from or corroborated by observable market data by correlation or other means; and • Level 3: Uses inputs that are unobservable and require the Company to make certain assumptions and require significant estimation and judgment from management to use in pricing the fair value of the assets and liabilities. As of December 31, 2017 and 2016, there were no assets or liabilities measured at Level 3 on a recurring basis. Certain financial instruments, including cash and cash equivalents, contract receivables, and accounts payable are carried at cost, which, due to their short maturities, approximates their fair values at December 31, 2017 and 2016. The carrying value of other long-term liabilities related to capital expenditure obligations approximates their fair value at December 31, 2017 and 2016 based on the current rates offered to the Company for similar instruments with comparable maturities (Level 2). The Company believes the carrying value of its Credit Facility at December 31, 2017 and 2016 approximates the estimated fair value for debt with similar terms, interest rates, and remaining maturities currently available to companies with similar credit ratings (Level 2). The Company applies the provisions of ASC 820 to its assets and liabilities that are required to be measured at fair value pursuant to other accounting standards, including assets and liabilities resulting from the Company’s nonqualified deferred compensation plan, interest rate swap agreement (see Note 9—Derivative Instruments and Hedging Activities), and foreign currency forward contract agreements not eligible for hedge accounting. The impact of the amounts recorded for the nonqualified deferred compensation plan, interest rate swap agreement, and the forward contract agreements was immaterial to the consolidated financial statements.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 17—COMMITMENTS AND CONTINGENCIES Litigation and Claims The Company is involved in various legal matters and proceedings arising in the ordinary course of business. While these matters and proceedings cause it to incur costs, including, but not limited to, attorneys’ fees, the Company currently believes that any ultimate liability arising out of these matters and proceedings will not have a material adverse effect on the Company’s financial position, results of operations, or cash flows. Road Home Contract On June 10, 2016, the Office of Community Development (the “OCD”) of the State of Louisiana filed a written administrative demand with the Louisiana Commissioner of Administration against ICF Emergency Management Services, L.L.C. (“ICF Emergency”), a subsidiary of the Company, in connection with ICF Emergency’s administration of the Road Home Program (the “Program”). The Program contract was a three-year, $912 million contract awarded to the Company in 2006 and that ended, as scheduled, in 2009. The Program was primarily intended to help homeowners and landlords of small rental properties affected by Hurricanes Rita and Katrina. In its administrative demand, the OCD sought approximately $200.8 million in alleged overpayments to Program grant recipients. The State separately supplemented the amount of recovery it is seeking in total approximately $220.2 million. The State of Louisiana, through the Division of Administration, also filed suit in Louisiana state court on June 10, 2016 broadly alleging and seeking recoupment for the same claim made in the administrative proceeding submission before the Louisiana Commissioner of Administration. On September 21, 2016, the Commissioner of the Division of Administration notified OCD and the Company of his decision to defer jurisdiction of the administrative demand filed by the OCD. In so doing, the Commissioner declined to reach a decision on the merits, stated that his deferral would not be deemed to grant or deny any portion of the OCD’s claim, and authorized the parties to proceed on the matter in the previously filed judicial proceeding. The Company continues to believe that this claim has no merit, intends to vigorously defend its position, and has therefore not recorded a liability as of December 31, 2017. Operating Leases On March 8, 2010, the Company entered into a new lease that replaced its prior headquarters lease, which was due to expire in October 2012. The new lease was initially for approximately 258,000 square feet, with approximately 72,000 square feet of additional space subsequently added. The lease commenced on April 1, 2010, and will expire on December 31, 2022. Base rent under the agreement is approximately $0.9 million per month with annual escalations fixed at 2.5% per year, yielding a total lease commitment of approximately $150.6 million over the twelve-year term of the lease. The Company has entered into various other operating leases for equipment and office space. Certain facility leases may contain fixed escalation clauses, certain facility leases require the Company to pay operating expenses in addition to base rental amounts, and nine leases require the Company to maintain letters of credit. Future minimum rental payments under all non-cancelable operating leases are as follows: Year ending December 31, (in thousands) 2018 $ 36,238 2019 34,223 2020 31,459 2021 31,091 2022 29,761 Thereafter 30,998 $ 193,770 Minimum lease payments have been reduced by minimum sublease rentals of $1.4 million due in the future under non-cancelable subleases. Rent expense is recognized on a straight-line basis over the lease term, net of sublease payments. Rent expense consists of the following for the years ended December 31: (in thousands) 2017 2016 2015 Rent $ 36,269 $ 39,537 $ 40,009 Sublease income (142 ) (147 ) (32 ) Total rent expense $ 36,127 $ 39,390 $ 39,977

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Benefit Plans	NOTE 18—EMPLOYEE BENEFIT PLANS Retirement Savings Plan Effective June 30, 1999, the Company established the ICF Consulting Group Retirement Savings Plan (the “Retirement Savings Plan”). The Retirement Savings Plan is a defined contribution profit sharing plan with a cash or deferred arrangement under Section 401(k) of the Internal Revenue Code. Participants in the Retirement Savings Plan are able to elect to defer up to 70% of their compensation subject to statutory limitations, and are entitled to receive 100% employer matching contributions for the first 3% and 50% for the next 2% of their compensation. Contribution expense related to the Retirement Savings Plan for the years ended December 31, 2017, 2016, and 2015, was approximately $15.1 million, $14.9 million, and $13.1 million, respectively. Deferred Compensation Plan Certain key employees of the Company are eligible to defer a specified percentage of their cash compensation by having it contributed to a nonqualified deferred compensation plan. Eligible employees may elect to defer up to 80% of their base salary and up to 100% of performance bonuses, reduced by any amounts withheld for the payment of taxes or other deductions required by law. Participants are at all times 100% vested in their account balances. The Company funds its deferred compensation liabilities by making cash contributions to a Rabbi Trust at the time the salary or bonus being deferred would otherwise be payable to the employee. The liability to plan participants is materially funded at all times and the plan does not have a material net impact on the Company’s results of operations. Employee Stock Purchase Plan The Company has a 2006 Employee Stock Purchase Plan (“ESPP”) under which one million shares have been authorized for issuance. The ESPP allows eligible employees to purchase shares of our common stock through payroll deductions up to $25,000 per calendar year over six-month offering periods at a discount not to exceed 5% of the market value on the date of each purchase period. For the year ended December 31, 2017, 27,285 shares were purchased by employees, at an average purchase price of $47.34, and 724,826 shares remain available for future issuance. The Company does not recognize compensation expense related to the ESPP.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	NOTE 19—SUBSEQUENT EVENTS In January 2018, the Company acquired The Future Customer, a leading boutique loyalty strategy and marketing company based in London. The acquisition was immaterial to the financial statements taken as a whole. On February 27, 2018, the Company’s board of directors approved a $0.14 per share cash dividend. The dividend will be paid on April 16, 2018 to shareholders of record as of the close of business on March 30, 2018.

Supplemental Information

Supplemental Information	12 Months Ended
	Dec. 31, 2017
Disclosure Text Block Supplement [Abstract]
Supplemental Information	NOTE 20—SUPPLEMENTAL INFORMATION Valuation and Qualifying Accounts Allowance for Doubtful Accounts 2017 2016 2015 Balance at beginning of period $ 2,591 $ 2,138 1,887 Bad debt expense 1,480 1,089 268 Write-offs, net of recoveries (219 ) (635 ) (8 ) Effect of foreign currency translation 1 (1 ) (9 ) Balance at end of period $ 3,853 $ 2,591 $ 2,138 Income Tax Valuation Allowance 2017 2016 2015 Balance at beginning of period $ 1,131 $ 933 542 Provision for income taxes - valuation allowance 505 198 391 Balance at end of period $ 1,636 $ 1,131 $ 933

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	NOTE 21—SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) 2017 2016 1Q 2Q 3Q 4Q 1Q (1) 2Q 3Q 4Q Contract revenue $ 296,295 $ 306,392 $ 305,301 $ 321,174 $ 283,599 $ 305,419 $ 306,520 $ 289,559 Operating income $ 16,633 $ 22,208 $ 23,396 $ 20,181 $ 17,694 $ 19,358 $ 23,776 $ 21,965 Net income $ 10,177 $ 11,937 $ 13,692 $ 27,070 $ 9,891 $ 10,583 $ 13,437 $ 12,673 Earnings per share: Basic $ 0.54 $ 0.64 $ 0.73 $ 1.45 $ 0.52 $ 0.56 $ 0.71 $ 0.67 Diluted $ 0.52 $ 0.63 $ 0.72 $ 1.41 $ 0.51 $ 0.55 $ 0.70 $ 0.65 Weighted-average common shares outstanding (in thousands) Basic 18,972 18,775 18,666 18,646 18,994 19,008 18,965 18,988 Diluted 19,423 19,086 19,024 19,136 19,273 19,293 19,329 19,512 (1) Includes adjustments for the adoption ASU 2016-09 in the second quarter of 2016.

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and contingent liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when persuasive evidence of an arrangement exists, services have been rendered, the contract price is fixed or determinable, and collectability is reasonably assured. The Company enters into three types of contracts: time-and-materials, cost-based, and fixed-price. • Time-and-Materials Contracts. • Cost-Based Contracts . • Fixed-Price Contracts . • Proportional Performance: progress towards completion can be measured based on a reliable output or input. • Specific Performance : hen the services to be performed consist of a single act, revenue is recognized at the time the act is performed or at the completion of the single service. • Straight-Line • Completed Contract Revenue recognition requires the Company to use judgment relative to assessing risks, estimating contract revenue and costs or other variables, and making assumptions for scheduling and technical issues. Due to the size and nature of many of the Company’s contracts, the estimation of revenue and the cost to perform for contracts in process can be complicated and subject to many variables. Contract costs include labor, subcontractor costs, and other direct costs, as well as an allocation of indirect costs. At times, the Company must also make assumptions regarding the length of time to complete the contract because costs include expected increases in wages, prices for subcontractors, and other direct costs. From time to time, the Company obtains new information which causes it to revise its estimated total costs or hours to fulfill contract requirements and thus the associated revenue earned on a contract. To the extent that a revised estimate affects contract profit or revenue previously recognized, the Company records the cumulative effect of the revision in the period in which the facts requiring the revision become known. A provision for the full amount of an anticipated loss on any type of contract is recognized in the period in which the anticipated loss becomes probable and can be reasonably estimated. As a result, operating results could be affected by revisions to prior accounting estimates. Contractual arrangements are evaluated to assess whether revenue should be recognized on a gross versus net basis. Management’s assessment when determining gross versus net revenue recognition is based on several factors, such as whether the Company serves as the primary service provider, has autonomy in selecting subcontractors, or has credit risk, all of which are primary indicators that the Company serves as the principal to the transaction. In such cases, revenue is recognized on a gross basis. When such indicators are not present and the Company is primarily functioning as an agent under an arrangement, revenue is recognized on a net basis, being limited to fees earned for facilitating the transaction. Payments to the Company on cost-based contracts with the U.S. federal government are provisional payments subject to audit and adjustment by the government. Indirect costs applied to government contracts are also subject to audit and adjustment and such audits have been finalized only through December 31, 2007. Contract revenue has been recorded in amounts that are expected to be realized on final audit and settlement of costs. The Company prepares client invoices in accordance with the terms of the applicable contract, and billing terms may not be directly related to the performance of services. Unbilled receivables are invoiced based on the achievement of specific events as defined by each contract, including deliverables, timetables, and incurrence of certain costs. Unbilled receivables are classified as a current asset. Advanced billings to clients in excess of revenue earned are recorded as deferred revenue until the revenue recognition criteria are met. Reimbursements of out-of-pocket expenses are included in revenue when the corresponding costs are included in the cost of revenue. The Company records revenue net of taxes collected from clients when the taxes are to be remitted to governmental authorities. The Company may proceed with work based on client direction prior to the completion and signing of formal contract documents. The Company has a review process for approving any such work. Revenue associated with such work is recognized only when it can be reliably estimated and realization is probable. The Company bases its estimates on a variety of factors, including previous experiences with the client, communications with the client regarding contract status, and its knowledge of the likelihood that contractual limits, or funding, will be increased.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers cash on deposit and all highly liquid investments with original maturities of three months or less when purchased to be cash and cash equivalents.
Restricted Cash	Restricted Cash The Company has restricted cash representing amounts held in escrow accounts and/or not readily available due to contractual restrictions.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company considers a number of factors in its estimate of allowance for doubtful accounts, including the customer’s financial condition, historical collection experience, and other factors that may bear on collectability of the receivables. The Company writes off contract receivables when such amounts are determined to be uncollectible.
Property and Equipment	Property and Equipment Property and equipment are carried at cost and are depreciated using the straight-line method over their estimated useful lives, which range from two to seven years. Leasehold improvements are amortized on a straight-line basis over the shorter of the economic life of the improvement or the related lease term.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The purchase price of an acquired business is allocated to the tangible assets and separately identifiable intangible assets acquired, less liabilities assumed, based on their respective fair values, with the excess recorded as goodwill. Goodwill represents the excess of costs over the fair value of net assets of businesses acquired. Goodwill and intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized, but instead are reviewed for impairment annually, or more frequently if impairment indicators arise. Intangible assets with estimable useful lives are amortized over such lives and reviewed for impairment if impairment indicators arise.
Impairment	Impairment The Company has historically performed its annual goodwill impairment test as of September 30 of each year. Effective for the annual goodwill impairment test for 2017, the Company performed the required annual test as of October 1. During the fourth quarter of 2017, the Company early adopted the Accounting Standards Update 2017-04, Intangibles—Goodwill and Other (Topic 350) (ASU 2017-04) issued by the Financial Accounting Standards Board (the “FASB”). ASU 2017-04 simplified the calculation and recognition of impairment of goodwill if there is evidence of an impairment based on qualitative or quantitative assessments by eliminating Step 2 of the two step impairment test required by the prior accounting standard. For the purposes of performing the annual goodwill impairment test, the Company has one reporting unit. For the goodwill impairment test as of October 1, 2017, the Company opted to perform a qualitative assessment of whether it is more likely than not that its reporting unit's fair value is less than its carrying amount. If, after completing its qualitative assessment, the Company determines that it is more likely than not that the estimated fair value of the reporting unit exceeded its carrying amount, it may conclude that no impairment exists. If the Company concludes otherwise, a goodwill impairment test must be performed, which includes a comparison of the reporting unit’s fair value to the carrying amount and recognizing as an impairment loss the difference of the reporting unit’s fair value and the carrying amount of goodwill. The Company’s qualitative analysis as of October 1, 2017 included macroeconomic, industry and market specific considerations, financial performance indicators and measurements, and other factors. Based on this qualitative assessment, the Company determined that it is more likely than not that the fair value of its reporting unit exceeded its carrying amount, and thus the impairment test was not required to be performed. Therefore, based on management’s review, a goodwill impairment loss was not required for 2017. Historically, the Company has not recorded any goodwill impairment losses. The Company is required to review long-lived assets and certain identifiable intangibles for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset might not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to future undiscounted net cash flows expected to be generated by the asset. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset exceeds its fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less cost to sell.
Capitalized Software	Capitalized Software The Company capitalizes eligible costs to develop enhancements and upgrades to internal-use software that are incurred subsequent to the preliminary project stage. Amortization expense is recorded on a straight-line basis over the expected economic life of the software, typically lasting three to five years. During the years ended December 31, 2017, 2016, and 2015, the costs capitalized for the development of internal-use software were not material to the Company’s consolidated financial statements.
Deferred Rent	Deferred Rent The Company recognizes rent expense on a straight-line basis over the non-cancellable term of each lease, including renewal option periods when renewal is reasonably assured or executed. Lease incentives or abatements received at or near the inception of leases are accrued and amortized ratably over the life of the lease.
Stock-based Compensation	Stock-based Compensation The Company recognizes stock-based compensation expense related to share-based payments to employees, including grants of employee stock options, restricted stock awards, restricted stock units (“RSUs”), and cash-settled restricted stock units (“CSRSUs”) on a straight-line basis over the requisite service period, which is generally the vesting period. The Company recognizes expense for performance-based share awards (“PSAs”), which have both a performance and condition, on a straight-line basis over the three-year performance period. Non-employee director awards, which do not include vesting conditions, are for board-related services and therefore expensed when earned. Stock-based compensation expense is based on the estimated fair value of the instruments on award and the estimated number of shares the Company ultimately expects will vest. The Company estimates the rate of future forfeitures based on factors such as historical experience and employee class. In addition, the estimation of PSAs that will ultimately vest requires judgment based on the performance and market conditions that will be achieved over the performance period. Changes to these estimates are recorded as a cumulative adjustment in the period estimates are revised. The fair value of stock options, restricted stock awards, RSUs, PSAs, and non-employee director awards is estimated based on the fair value of a share of common stock at the grant date. The Company has elected to use the Black-Scholes-Merton option pricing model to determine the fair value of stock options. The fair value of PSAs is estimated using a Monte Carlo simulation model. CSRSUs are settled only in cash payments. The cash payment is based on the fair value of the Company’s stock price at the vesting date, calculated by multiplying the number of CSRSUs vested by the Company’s closing stock price on the vesting date, subject to a maximum payment cap and a minimum payment floor. The Company treats these awards as liability-classified awards, and, therefore, accounts for them at fair value estimated based on the closing price of the Company’s stock at the reporting date.
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Other comprehensive income (loss) represents foreign currency translation adjustments arising from the use of differing exchange rates from period to period and the gain on the sale of an interest rate hedge agreement. The financial positions and results of operations of the Company’s foreign subsidiaries are based on the local currency as the functional currency and are translated to U.S. dollars for financial reporting purposes. Assets and liabilities of the subsidiaries are translated at the exchange rate in effect at each balance sheet date. Income statement accounts are translated at the average rate of exchange prevailing during the period. Translation adjustments are reported in accumulated other comprehensive loss included in stockholders’ equity in the Company’s consolidated balance sheets. The activity included in other comprehensive income (loss), net of tax, in the Company’s consolidated statements of comprehensive income for each period reported is summarized below. Year ended December 31, 2017 2016 2015 Foreign currency translation adjustments $ 4,177 $ (4,321 ) $ (5,676 ) Foreign currency realized losses reclassified into earnings — (3 ) 666 Change in fair value of derivative designated as cash flow hedge 441 — — Gain on sale of interest rate hedging agreement, net of tax (1) (17 ) 2,175 — Other comprehensive income (loss), net of tax (2) $ 4,601 $ (2,149 ) $ (5,010 ) ( 1 ) On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge was recorded in other comprehensive income (loss), net of tax, and will be reclassified to earnings when earnings are impacted by the cash flows of the hedged items, the interest payments on the Credit Facility or its replacement from January 31, 2018 to January 31, 2023. See additional details on the hedge agreement in Note 9—Derivative Instruments and Hedging Activities. ( 2 ) Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.
Derivative Instruments	Derivative Instruments Derivative instruments designated as cash flow hedges are recorded on the consolidated balance sheet at fair value as of the reporting date, and the effective portion of the hedge is recorded in other comprehensive income (loss) on the consolidated statement of comprehensive income and reclassified to earnings in the period that the hedged instruments affect earnings. Management reviews the effectiveness of the hedges on a quarterly basis.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The Company evaluates its ability to benefit from all deferred tax assets and establishes valuation allowances for amounts it believes will more likely than not be unrealizable. For uncertain tax positions, the Company uses a more-likely-than-not recognition threshold based on the technical merits of the income tax position taken. Income tax positions that meet the more-likely-than-not recognition threshold are measured in order to determine the tax benefit recognized in the financial statements.
Treasury Shares	Treasury Shares Treasury shares are accounted for under the cost method.
Segment Customer and Geographic Information	Segment, Customer and Geographic Information The Company operates in one segment based on the consolidated information used by its chief operating decision maker in evaluating the financial performance of its business and allocating resources. This single segment represents the Company’s core business which is providing professional services for government and commercial clients. Although, in order to provide insight into the breadth of its capabilities and diversity of its client base, the Company describes its clients’ four key market areas and evaluates its revenue based on the type of client served, the Company does not manage its business or allocate resources based on those service offerings or types of clients. Approximately $550.3 million, $563.0 million, and $540.0 million of the Company’s revenue for the years 2017, 2016, and 2015, respectively, was derived under prime contracts and subcontracts with agencies and departments of the federal government representing 45%, 48%, and 48% of total revenue, respectively. No other customer accounted for 10% or more of the Company’s revenue during the years ended 2017, 2016, and 2015, respectively. The Company’s international operations provide services to both commercial and international government clients. Revenue is attributed to a particular geographic area based on the administrative location of the client that awarded the contract. The Company’s revenue generated from international clients as a percentage of total revenue was approximately 9%, 10%, and 11% for the years 2017, 2016, and 2015, respectively. At December 31, 2017 and 2016, long-lived assets held internationally were not material.
Risk and Uncertainties	Risks and Uncertainties Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash and cash equivalents and contract receivables. The majority of the Company’s cash transactions are processed through one U.S. commercial bank. Cash held domestically in excess of daily requirements is used to reduce any amounts outstanding under the Company’s Credit Facility. As of December 31, 2017 and 2016, the Company held approximately $10.4 million and $5.4 million, respectively, of cash in foreign bank accounts. To date, the Company has not incurred losses related to cash and cash equivalents. The Company’s contract receivables consist principally of receivables from agencies and departments of, as well as from prime contractors to, the U.S. federal, state and local, and international governments, as well as from commercial organizations. The Company believes that this respect to federal and other governments, including when the Company is a subcontractor to a prime contractor, The Company has historically been, and continues to be, heavily dependent on contracts with the federal government and is subject to audit, in particular, by agencies of the federal government. Such audits determine, among other things, whether an adjustment of invoices rendered to the government is appropriate under the underlying terms of the contracts. Management does not expect any significant adjustments as a result of government audits that will adversely affect the Company’s financial position.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recent Accounting Pronouncements Adopted Cash Receipts and Cash Payments In August 2016, FASB issued Accounting Standard Update (“ASU”) 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments that addressed eight specific cash flow issues to reduce the existing diversity in practice. During the third quarter of 2017, the Company elected to early adopt ASU 2016-15, which did not have a material impact on the Company’s consolidated financial statements. Restricted Cash In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force), which requires entities to show the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash and cash equivalents in the statement of cash flows. During the third quarter of 2017, the Company elected to early adopt ASU 2016-18 retrospectively, with adjustments to the 2016 and 2015 fiscal years’ consolidated statements of cash flows. The impact of the adoption on the Company’s previously reported consolidated statements of cash flows is summarized as follows: Year Ended December 31, 2016 Year Ended December 31, 2015 As Reported As Adjusted As Reported As Adjusted Restricted cash $ (494 ) $ — $ 116 $ — Net Cash Provided by Operating Activities 79,563 80,057 76,319 76,203 Effect of exchange rate changes on cash (403 ) (416 ) (1,746 ) (1,746 ) (Decrease) Increase in Cash and Cash Equivalents (1,705 ) — (4,375 ) — Increase in Cash, Cash Equivalents, and Restricted Cash — (1,224 ) — (4,491 ) Cash and Cash Equivalents, Beginning Period 7,747 — 12,122 — Cash, Cash Equivalents, and Restricted Cash, Beginning Period — 9,109 — 13,600 Cash and Cash Equivalents, End of Period 6,042 — 7,747 — Cash, Cash Equivalents, and Restricted Cash, End of Period — 7,885 — 9,109 Goodwill In January 2017, the FASB issued ASU 2017-04, Intangibles – Goodwill and Other (Topic 350) (ASU 2017-04), which simplifies the measurement of goodwill during the execution of a goodwill impairment test in the event that there is evidence of an impairment based on qualitative or quantitative assessments. ASU 2017-04 does not change how the goodwill impairment is identified, and the Company will continue to perform a qualitative assessment annually to determine whether the two-step impairment test is required. The previous accounting standard required the impairment loss to be recognized under Step 2 of the impairment test. This required the Company to determine whether the carrying amount of the reporting unit’s goodwill exceeds its implied fair value. The implied fair value was calculated by assigning the fair value of the reporting unit to all of its assets and liabilities as if it had been acquired in a business combination. The new standard requires the Company to determine the fair value of the reporting unit and subtract the carrying amount from the fair value of the reporting unit to determine if there is any impairment. If the Company concludes that an impairment exists, an impairment loss will be recorded reflecting the difference of the reporting unit’s estimated fair value over its carrying amount. During the fourth quarter of 2017, the Company elected to early adopt ASU 2017-04, which did not have a material impact on the Company’s consolidated financial statements. Derivative and Hedging In August 2017, the FASB issued ASU 2017-12: Derivatives and Hedging (Topic 815) (ASU 2017-12). ASU 2017-12’s objective is to improve the financial reporting of an entity’s hedges and better aligns an entity’s hedge accounting with the entity’s risk management strategies, as well as simplify the current hedge accounting guidance. During the fourth quarter of 2017, the Company elected to early adopt ASU 2017-12, which did not have a material impact on the Company’s consolidated financial statements. Recent Accounting Pronouncements Not Yet Adopted Revenue Recognition In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). ASU 2014-09 provides a single comprehensive revenue recognition framework and supersedes existing revenue recognition guidance. Included in the new principles-based revenue recognition model are changes to the basis for determining the timing for revenue recognition. In addition, the standard expands and improves revenue disclosures. In August 2015, the FASB issued ASU 2015-14 to amend ASU 2014-09 in order to defer the effective date of the new standard. In accordance with this update, the Company elected to adopt the requirements of the new standard effective January 1, 2018. The Company has evaluated the impact of the new guidance on the timing of revenue and expanded disclosure requirements. The Company has concluded that, for the majority of its contracts, there is no material change in the timing of revenue recognition. However, the new standard will result in a change in revenue timing for performance incentives under certain contracts. Under the prior guidance, performance incentives were recognized as revenue when specific quantitative goals were achieved, generally at the end of a measurement period. Under the new standard, these incentives are considered variable consideration and the Company will include in revenue the most likely amount of the priced incentives to be earned as contract work is performed and recognize revenue associated with the incentives over the term of the agreement. This change is not expected to result in a material change to the Company’s annual revenue since most incentives have a one-year measurement period which is aligned with the Company’s fiscal year, but the change may accelerate revenue recognized on a quarterly basis. As of January 1, 2018, the Company adopted the standard using the modified retrospective transition method. Under the modified retrospective method, the new standard applies to new contracts and those that were not completed as of January 1, 2018. For those contracts not completed as of January 1, 2018, the Company is finalizing the catch-up adjustment to retained earnings but does not expect the transition adjustment to be material to the consolidated financial statements. Total net cash provided by operating activities and net cash used by investing and financing activities will not be impacted by the adoption of the new standard. Prior periods will not be retrospectively adjusted, but the Company will maintain dual reporting for the year of initial application in order to disclose the effect on revenue of adopting the new guidance. Additional disclosures under the new standard will, among other required disclosures, disaggregate revenue into categories that reflect how the nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factors. Leases In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). This update revises an entity’s accounting for operating leases and requires lessees to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. This update also requires that lessees recognize assets and liabilities on the balance sheet for the rights and obligations created by all such leases and requires disclosures designed to give financial statement users information on the amount and timing of lease expenses arising from such leases. These disclosures include certain qualitative and specific quantitative disclosures. For lessees, the new guidance is not expected to significantly change the recognition, measurement, and presentation of expenses arising from a lease. This update is effective for the first interim and annual periods beginning after December 15, 2018, with early adoption permitted. The Company continues to evaluate the impact of adopting ASU 2016-02, the elections to be made at adoption in a modified retrospective approach, the impact of future modifications to the new accounting pronouncement, our inventory of operating leases, the software options that will aid in the implementation and accounting under the new accounting pronouncement, and the timing of adoption. Accumulated other comprehensive In February 2018, the FASB issued ASU 2018-02: Income Statement – Reporting Comprehensive Income (Topic 220) (ASU 2018-02). ASU 2018-02’s objective is to address the application of ASC 740 to certain provisions of the new tax reform legislation commonly known as Tax Cuts and Jobs Act (the “Tax Act”). ASC 740 requires the effect of a change in tax rates on deferred assets and liabilities be included in income from continuing operations in the reporting period that contains the enactment date of the change. The guidance applies even in situations in which the tax effects were initially recognized directly in other comprehensive income at the previous rate, resulting in a stranded amount in accumulated other comprehensive income (loss) (AOCI) related to the income tax rate differential. ASU 2018-02 requires the Company to reclassify the amount of stranded taxes in AOCI to retained earnings. This update is effective for fiscal years beginning after December 15, 2018, including interim periods therein, and early adoption is permitted. The Company is currently evaluating the impact of the pronouncement on the consolidated financial statements.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Other Comprehensive Income (Loss) Net of Tax Activity	. The activity included in other comprehensive income (loss), net of tax, in the Company’s consolidated statements of comprehensive income for each period reported is summarized below. Year ended December 31, 2017 2016 2015 Foreign currency translation adjustments $ 4,177 $ (4,321 ) $ (5,676 ) Foreign currency realized losses reclassified into earnings — (3 ) 666 Change in fair value of derivative designated as cash flow hedge 441 — — Gain on sale of interest rate hedging agreement, net of tax (1) (17 ) 2,175 — Other comprehensive income (loss), net of tax (2) $ 4,601 $ (2,149 ) $ (5,010 ) ( 1 ) On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge was recorded in other comprehensive income (loss), net of tax, and will be reclassified to earnings when earnings are impacted by the cash flows of the hedged items, the interest payments on the Credit Facility or its replacement from January 31, 2018 to January 31, 2023. See additional details on the hedge agreement in Note 9—Derivative Instruments and Hedging Activities. ( 2 ) Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.
Summary of Previously Reported Consolidated Statement of Cash Flows	The impact of the adoption on the Company’s previously reported consolidated statements of cash flows is summarized as follows: Year Ended December 31, 2016 Year Ended December 31, 2015 As Reported As Adjusted As Reported As Adjusted Restricted cash $ (494 ) $ — $ 116 $ — Net Cash Provided by Operating Activities 79,563 80,057 76,319 76,203 Effect of exchange rate changes on cash (403 ) (416 ) (1,746 ) (1,746 ) (Decrease) Increase in Cash and Cash Equivalents (1,705 ) — (4,375 ) — Increase in Cash, Cash Equivalents, and Restricted Cash — (1,224 ) — (4,491 ) Cash and Cash Equivalents, Beginning Period 7,747 — 12,122 — Cash, Cash Equivalents, and Restricted Cash, Beginning Period — 9,109 — 13,600 Cash and Cash Equivalents, End of Period 6,042 — 7,747 — Cash, Cash Equivalents, and Restricted Cash, End of Period — 7,885 — 9,109

Contract Receivables (Tables)

Contract Receivables (Tables)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Summary of Contract Receivables	Contract receivables consisted of the following at December 31: 2017 2016 Billed $ 169,027 $ 168,012 Unbilled 117,037 108,432 Retainages 6,160 5,088 Other 3,144 2,424 Allowance for doubtful accounts (3,853 ) (2,591 ) Contract receivables, net $ 291,515 $ 281,365

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Property and Equipment	Property and equipment consisted of the following at December 31: 2017 2016 Leasehold improvements $ 18,873 $ 17,847 Software 42,835 41,269 Furniture and equipment 26,076 26,570 Computers 28,826 28,874 116,610 114,560 Accumulated depreciation and amortization (78,558 ) (74,076 ) Total property and equipment, net $ 38,052 $ 40,484

Goodwill and Other Intangible32

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Changes in Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the fiscal years ended December 31 were as follows: 2017 2016 Balance as of January 1 $ 683,683 $ 687,404 Goodwill resulting from the Trade NTE business combination — 191 Goodwill resulting from the Mostra business combination — 654 Goodwill resulting from the Olson business combination — 267 Effect of foreign currency translation 2,425 (4,833 ) Total goodwill $ 686,108 $ 683,683
Schedule of Other Intangibles	Other intangibles consisted of the following at December 31: 2017 Gross Carrying Value Accumulated Amortization Net Carrying Value Customer-related $ 84,878 $ (49,782 ) $ 35,096 Developed technology 1,463 (1,350 ) 113 Total amortizable intangible assets 86,341 (51,132 ) 35,209 Intangible with indefinite life 95 — 95 Total other intangible assets $ 86,436 $ (51,132 ) $ 35,304 2016 Gross Carrying Value Accumulated Amortization Net Carrying Value Customer-related $ 115,806 $ (70,090 ) $ 45,716 Developed technology 1,463 (1,145 ) 318 Total amortizable intangible assets 117,269 (71,235 ) 46,034 Intangible with indefinite life 95 — 95 Total other intangible assets $ 117,364 $ (71,235 ) $ 46,129
Schedule of Estimated Future Amortization Expense Relating to Intangible Assets	The estimated future amortization expense relating to intangible assets is as follows: Year ending December 31, 2018 $ 8,441 2019 6,132 2020 4,532 2021 4,082 2022 4,125 Thereafter 7,897 Total $ 35,209

Accrued Salaries and Benefits (

Accrued Salaries and Benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Employee Related Liabilities Current [Abstract]
Schedule of Accrued Salaries and Benefits	Accrued salaries and benefits consisted of the following at December 31: 2017 2016 Accrued paid time off and leave $ 11,904 $ 11,342 Accrued salaries 9,343 9,443 Accrued bonuses, liability-classified awards and commissions 16,909 13,025 Accrued payroll taxes and withholdings 2,557 1,948 Accrued medical 3,720 3,026 Other 1,212 979 Total accrued salaries and benefits $ 45,645 $ 39,763

Accrued Expenses and Other Cu34

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following at December 31: 2017 2016 Accrued subcontractor and other direct costs $ 47,508 $ 30,153 Deposits 6,641 12,389 Accrued IT and software licensing costs 2,261 5,349 Accrued taxes and insurance premiums 1,963 1,306 Accrued lease exit and facilities costs 1,591 77 Accrued interest 705 841 Accrued professional services 1,131 795 Other accrued expenses and current liabilities 3,280 1,721 Total accrued expenses and other current liabilities $ 65,080 $ 52,631

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt outstanding and the weighted average interest rate at December 31 is summarized as follows: 2017 2016 Debt Outstanding Weighted Average Interest Rate Debt Outstanding Weighted Average Interest Rate Revolving Line of Credit/Swing Line $ 206,250 2.65 % $ 259,389 2.46 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Before Income Taxes	The domestic and foreign components of income before provision for income taxes are as follows for the years ended December 31: 2017 2016 2015 Domestic $ 69,347 $ 69,159 $ 54,150 Foreign 4,639 5,348 9,450 Income before income taxes $ 73,986 $ 74,507 $ 63,600
Income Tax Expense Components	Income tax expense consisted of the following for the years ended December 31: 2017 2016 2015 Current: Federal $ 12,995 $ 12,979 $ 14,797 State 3,243 3,514 2,669 Foreign 1,476 1,932 1,475 Total current 17,714 18,425 18,941 Deferred: Federal (9,425 ) 8,872 4,562 State 2,749 1,222 512 Foreign 72 (596 ) 216 Total deferred (6,604 ) 9,498 5,290 Income tax expense $ 11,110 $ 27,923 $ 24,231
Deferred Tax Assets (Liabilities)	Deferred tax assets (liabilities) consisted of the following at December 31: 2017 2016 Deferred Tax Assets Allowance for bad debt $ 1,003 $ 1,008 Accrued paid time off 1,624 2,592 Accrued bonus — 55 Foreign net operating loss (NOL) carry forward 1,301 1,371 Federal/state net operating loss (NOL) carry forward 507 3,010 Stock option compensation 2,726 4,292 Deferred rent 3,355 5,423 Deferred compensation 3,238 3,662 Foreign tax credits 505 2,631 State tax credits 1,785 1,784 Federal tax credits — 225 Foreign exchange 2,051 5,349 Accrued liabilities and other 3,272 3,378 21,367 34,780 Less: Valuation Allowance (1,636 ) (1,131 ) Total Deferred Tax Assets 19,731 33,649 Deferred Tax Liabilities Retention (1,375 ) (1,684 ) Prepaid expenses (1,045 ) (1,654 ) Payroll taxes (489 ) (617 ) Unbilled revenue (5,407 ) (8,728 ) Depreciation (4,773 ) (6,664 ) Amortization (39,993 ) (51,842 ) Deferred gain and other — (1,574 ) Total Deferred Tax Liabilities (53,082 ) (72,763 ) Total Net Deferred Tax Liability $ (33,351 ) $ (39,114 )
Unrecognized Tax Benefit Reconciliation	The unrecognized tax benefit reconciliation, excluding penalty and interest, is as follows: Unrecognized tax benefits at January 1, 2015 $ 702 Decrease attributable to settlements (174 ) Increase attributable to tax positions taken during a prior period 12 Decrease attributable to lapse of statute of limitations (140 ) Unrecognized tax benefits at December 31, 2015 400 Increase attributable to tax positions taken during a prior period 925 Decrease attributable to lapse of statute of limitations (140 ) Unrecognized tax benefits at December 31, 2016 1,185 Decrease attributable to lapse of statute of limitations (365 ) Unrecognized tax benefits at December 31, 2017 $ 820
Effective Income Tax Rate Reconciliation	The Company’s provision for income taxes differs from the federal statutory rate. The differences between the statutory rate and the Company’s provision are as follows: 2017 2016 2015 Taxes at statutory rate 35.0 % 35.0 % 35.0 % State taxes, net of federal benefit 4.4 % 3.9 % 3.9 % Foreign tax rate differential (0.3 )% (0.1 )% (0.3 )% Tax legislation (22.6 )% — — Other permanent differences 0.7 % 0.8 % 1.9 % Prior year tax adjustments (0.3 )% (1.0 )% (1.9 )% Unrecognized tax benefits 0.1 % 1.0 % — Valuation allowance 0.7 % (0.3 )% — Equity-based compensation (2.1 )% (1.0 )% — Tax credits (0.6 )% (0.8 )% (0.5 )% Taxes at effective rate 15.0 % 37.5 % 38.1 %

Accumulated Other Comprehensi37

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Loss, Net of Tax	As of December 31, 2017 and 2016, accumulated other comprehensive loss, net of tax, included the following: 2017 2016 Foreign currency translation adjustments $ 7,638 $ 11,815 Gain on sale of interest rate hedge agreement (1) (2,158 ) (2,175 ) Change in fair value on derivative designated as cash flow hedge (2) (441 ) — Total $ 5,039 $ 9,640 (1) Represents the fair value of an interest rate hedge agreement, designated as a cash flow hedge, which was sold on December 1, 2016. The fair value of the interest rate hedge agreement was recorded in other comprehensive income, net of tax, and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities. (2) Represents the change in fair value of an interest rate hedge agreement designated as a cash flow hedge, and entered into on August 31, 2017. The fair value of the interest rate hedge agreement was recorded in other comprehensive income and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from August 31, 2018 to August 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.

Restricted Cash (Tables)

Restricted Cash (Tables)	12 Months Ended
	Dec. 31, 2017
Restricted Cash And Cash Equivalents Current [Abstract]
Reconciliation of Cash and Cash Equivalents, and Restricted Cash	The following table provides a reconciliation of cash and cash equivalents, and restricted cash reported within the consolidated balance sheets at December 31, 2017 and 2016 to the total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows for the years ended December 31, 2017, 2016, and 2015: 2017 2016 2015 Beginning Ending Beginning Ending Beginning Ending Cash and cash equivalents $ 6,042 $ 11,809 $ 7,747 $ 6,042 $ 12,122 $ 7,747 Restricted cash - current (1) — 11,191 — — — — Restricted cash - non-current 1,843 1,266 1,362 1,843 1,478 1,362 Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows $ 7,885 $ 24,266 $ 9,109 $ 7,885 $ 13,600 $ 9,109 (1) Restricted cash – current for the year ended December 31, 2017 represents amounts held in an escrow account for a future acquisition. See Note 19 – Subsequent Events.

Accounting for Stock-based Co39

Accounting for Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Stock-based Compensation Expense	The total stock-based compensation expense for the years ended December 31, 2017, 2016, and 2015, the unrecognized compensation expense at December 31, 2017, and the weighted-average period to recognize the remaining unrecognized shares are as follows: Stock-Based Compensation Expense Recognized as of December 31, Unrecognized 2017 2016 2015 December 31, 2017 Weighted-Average Period to Recognize (years) Stock Options $ 164 $ 909 $ 1,546 $ — — Restricted Stock Units 7,080 6,325 7,409 12,659 1.9 Cash-Settled Restricted Stock Units 7,253 7,091 4,414 13,922 1.9 Non-Employee Director Awards 671 741 645 — — Performance Shares 2,376 877 727 2,717 1.5 Total $ 17,544 $ 15,943 $ 14,741 $ 29,298
Outstanding Stock Option Activity	The following table summarizes the changes in outstanding stock options: Number of Shares Weighted Average Exercise Price Aggregate Intrinsic Value Outstanding at January 1, 2015 766,924 $ 28.20 Exercised (43,919 ) $ 21.23 Granted — $ — Forfeited/Expired — $ — Outstanding at December 31, 2015 723,005 $ 28.62 Exercised (128,301 ) $ 23.65 Granted — $ — Forfeited/Expired (7,297 ) $ 40.68 Outstanding at December 31, 2016 587,407 $ 29.56 Exercised (175,909 ) $ 26.84 Granted — $ — Forfeited/Expired — $ — Outstanding at December 31, 2017 411,498 $ 30.71 $ 8,965 Vested plus expected to vest at December 31, 2017 411,498 $ 30.71 $ 8,965 Exercisable at December 31, 2017 411,498 $ 30.71 $ 8,965
Schedule of Stock Options Outstanding by Exercise Price Range	Information regarding stock options outstanding as of December 31, 2017 is summarized below: OPTIONS OUTSTANDING OPTIONS EXERCISABLE Range of Exercise Prices Number Outstanding As of December 31, 2017 Weighted Average Remaining Contractual Term Weighted Average Exercise Price Number Exercisable As of December 31, 2017 Weighted Average Exercise Price $21.77 to $25.00 62,917 3.3 $ 21.77 62,917 $ 21.77 $25.01 to $28.00 205,332 4.8 $ 26.50 205,332 $ 26.50 $28.01 to $40.68 143,249 6.1 $ 40.68 143,249 $ 40.68 $21.77 to $41.00 411,498 5.0 $ 30.71 411,498 $ 30.71
Summary of Non-employee Director Awards Granted	A summary of the Company’s non-employee director awards granted by fiscal year is presented below. For the Year ended December 31, Number of shares Granted Weighted- Average Grant Date Fair Value 2015 18,109 $ 35.62 2016 15,299 $ 39.32 2017 13,861 $ 48.41
Summary of Performance Shares Activity	A summary of the Company’s PSAs is presented below. Number of Shares Weighted-Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested PSAs at January 1, 2015 — $ — Granted 58,822 $ 44.21 Vested — $ — Cancelled — $ — Non-vested PSAs at December 31, 2015 58,822 $ 44.21 Granted 74,574 $ 37.75 Vested — $ — Cancelled (3,422 ) $ 41.61 Non-vested PSAs at December 31, 2016 129,974 $ 40.57 Granted 60,929 $ 38.81 Vested — $ — Cancelled (3,881 ) $ 42.83 Non-vested PSAs at December 31, 2017 187,022 $ 39.95 $ 9,819 PSAs expected to vest in the future 126,846 $ 38.09 $ 6,659
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Restricted Stock Unit Activity	A summary of the Company’s RSUs is presented below. Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested RSUs at January 1, 2015 643,887 $ 31.10 Granted 250,159 $ 39.04 Vested (233,899 ) $ 26.85 Cancelled (104,243 ) $ 36.76 Non-vested RSUs at December 31, 2015 555,904 $ 35.40 Granted 240,868 $ 34.68 Vested (221,659 ) $ 32.45 Cancelled (67,115 ) $ 37.60 Non-vested RSUs at December 31, 2016 507,998 $ 36.12 Granted 194,227 $ 41.41 Vested (179,974 ) $ 35.19 Cancelled (58,664 ) $ 36.04 Non-vested RSUs at December 31, 2017 463,587 $ 38.71 $ 24,338 RSUs expected to vest in the future 463,587 $ 38.71 $ 24,338
Cash Settled RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Schedule of Restricted Stock Unit Activity	CSRSUs generally have a vesting term of four years. A summary of the Company’s CSRSUs is presented below. Number of Shares Weighted- Average Grant Date Fair Value Aggregate Intrinsic Value Non-vested CSRSUs at January 1, 2015 537,119 $ 36.36 Granted 121,015 $ 39.35 Vested (78,033 ) $ 33.29 Cancelled (133,438 ) $ 38.14 Non-vested CSRSUs at December 31, 2015 446,663 $ 37.18 Granted 233,790 $ 34.29 Vested (146,619 ) $ 34.70 Cancelled (70,812 ) $ 37.55 Non-vested CSRSUs at December 31, 2016 463,022 $ 35.96 Granted 174,419 $ 42.06 Vested (161,576 ) $ 40.78 Cancelled (83,949 ) $ 36.43 Non-vested CSRSUs at December 31, 2017 391,916 $ 38.80 $ 20,576 CSRSUs expected to vest in the future 391,916 $ 38.80 $ 20,576

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Dilutive Effect of Stock Options RSUs and PSAs	The dilutive effect of stock options, RSUs, and performance shares for each period reported is summarized below: (in thousands) 2017 2016 2015 Basic weighted-average shares outstanding 18,766 18,989 19,335 Effect of potential exercise of stock options, RSUs, and performance shares 478 427 328 Diluted weighted-average shares outstanding 19,244 19,416 19,663

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Year ending December 31, (in thousands) 2018 $ 36,238 2019 34,223 2020 31,459 2021 31,091 2022 29,761 Thereafter 30,998 $ 193,770
Operating Leases of Lessee Disclosure	(in thousands) 2017 2016 2015 Rent $ 36,269 $ 39,537 $ 40,009 Sublease income (142 ) (147 ) (32 ) Total rent expense $ 36,127 $ 39,390 $ 39,977

Supplemental Information (Table

Supplemental Information (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Text Block Supplement [Abstract]
Schedule of Allowance for Doubtful Accounts	Allowance for Doubtful Accounts 2017 2016 2015 Balance at beginning of period $ 2,591 $ 2,138 1,887 Bad debt expense 1,480 1,089 268 Write-offs, net of recoveries (219 ) (635 ) (8 ) Effect of foreign currency translation 1 (1 ) (9 ) Balance at end of period $ 3,853 $ 2,591 $ 2,138
Schedule of Income Tax Valuation Allowance	Income Tax Valuation Allowance 2017 2016 2015 Balance at beginning of period $ 1,131 $ 933 542 Provision for income taxes - valuation allowance 505 198 391 Balance at end of period $ 1,636 $ 1,131 $ 933

Selected Quarterly Financial 43

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	2017 2016 1Q 2Q 3Q 4Q 1Q (1) 2Q 3Q 4Q Contract revenue $ 296,295 $ 306,392 $ 305,301 $ 321,174 $ 283,599 $ 305,419 $ 306,520 $ 289,559 Operating income $ 16,633 $ 22,208 $ 23,396 $ 20,181 $ 17,694 $ 19,358 $ 23,776 $ 21,965 Net income $ 10,177 $ 11,937 $ 13,692 $ 27,070 $ 9,891 $ 10,583 $ 13,437 $ 12,673 Earnings per share: Basic $ 0.54 $ 0.64 $ 0.73 $ 1.45 $ 0.52 $ 0.56 $ 0.71 $ 0.67 Diluted $ 0.52 $ 0.63 $ 0.72 $ 1.41 $ 0.51 $ 0.55 $ 0.70 $ 0.65 Weighted-average common shares outstanding (in thousands) Basic 18,972 18,775 18,666 18,646 18,994 19,008 18,965 18,988 Diluted 19,423 19,086 19,024 19,136 19,273 19,293 19,329 19,512

Basis of Presentation and Nat44

Basis of Presentation and Nature of Operations - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2017Office
Reclassification of Deferred Compensation Liabilities from Accrued Salaries and Benefits to Long-term Noncurrent Classification
Basis of Presentation and Nature of Operations [Line Items]
Prior period reclassification adjustment | $	$ 4.3
Domestic
Basis of Presentation and Nature of Operations [Line Items]
Number of offices		59
International
Basis of Presentation and Nature of Operations [Line Items]
Number of offices		23

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Additional Information (Details)

3 Months Ended

12 Months Ended

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

[1]

Dec. 31, 2017USD ($)Segment

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Summary Of Significant Accounting Policies [Line Items]

Number of reportable segments | Segment

1

Goodwill, impaired, accumulated impairment loss

$ 0

$ 0

Goodwill, impairment loss

$ 0

Performance based share awards, performance period

3 years

Number of operating segments | Segment

1

Revenue

321,174,000

$ 305,301,000

$ 306,392,000

$ 296,295,000

$ 289,559,000

$ 306,520,000

$ 305,419,000

$ 283,599,000

$ 1,229,162,000

$ 1,185,097,000

$ 1,132,232,000

Foreign financial institutions, actual deposits

$ 10,400,000

$ 5,400,000

10,400,000

5,400,000

Federal Government Agencies And Departments

Summary Of Significant Accounting Policies [Line Items]

Revenue

$ 550,300,000

$ 563,000,000

$ 540,000,000

Federal Government Agencies And Departments | Customer Concentration Risk | Sales Revenue, Net

Summary Of Significant Accounting Policies [Line Items]

Concentration risk, percentage

45.00%

48.00%

48.00%

International Clients | Geographic Concentration Risk | Sales Revenue, Net

Summary Of Significant Accounting Policies [Line Items]

Concentration risk, percentage

9.00%

10.00%

11.00%

Minimum

Summary Of Significant Accounting Policies [Line Items]

Property and equipment, estimated useful life

2 years

Finite-lived intangible asset, useful life

4 years

Minimum | Other Assets

Summary Of Significant Accounting Policies [Line Items]

Finite-lived intangible asset, useful life

3 years

Maximum

Summary Of Significant Accounting Policies [Line Items]

Property and equipment, estimated useful life

7 years

Finite-lived intangible asset, useful life

10 years

Maximum | Other Assets

Summary Of Significant Accounting Policies [Line Items]

Finite-lived intangible asset, useful life

5 years

[1]

Includes adjustments for the adoption ASU 2016-09 in the second quarter of 2016.

Summary of Significant Accoun46

Summary of Significant Accounting Policies - Other Comprehensive Income (Loss) Net of Tax Activity (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Foreign currency translation adjustments		$ 4,177	$ (4,321)	$ (5,676)
Foreign currency realized losses reclassified into earnings			(3)	666
Change in fair value of derivative designated as cash flow hedge		441
Gain on sale of interest rate hedging agreement, net of tax(1)	[1]	(17)	2,175
Other comprehensive income (loss), net of tax	[2]	$ 4,601	$ (2,149)	$ (5,010)
[1]	On December 1, 2016, the Company sold the interest rate hedge agreement. The fair value of the interest rate hedge was recorded in other comprehensive income (loss), net of tax, and will be reclassified to earnings when earnings are impacted by the cash flows of the hedged items, the interest payments on the Credit Facility or its replacement from January 31, 2018 to January 31, 2023. See additional details on the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.
[2]	Net of tax of $1.0 million, $2.2 million, and $1.0 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Summary of Significant Accoun47

Summary of Significant Accounting Policies - Other Comprehensive Income (Loss) Net of Tax Activity (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Other comprehensive income (loss), tax	$ 1	$ 2.2	$ 1

Summary of Significant Accoun48

Summary of Significant Accounting Policies - Previously Reported Consolidated Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]
Net Cash Provided by Operating Activities	$ 117,191	$ 80,057	$ 76,203
Effect of exchange rate changes on cash	1,094	(416)	(1,746)
Increase in Cash, Cash Equivalents, and Restricted Cash	16,381	(1,224)	(4,491)
Cash and Cash Equivalents, Beginning Period	6,042	7,747	12,122
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	7,885	9,109	13,600
Cash and Cash Equivalents, End of Period	11,809	6,042	7,747
Cash, Cash Equivalents, and Restricted Cash, End of Period	24,266	7,885	9,109
New Accounting Pronouncement Early Adoption Effect | ASU 2016-18
Summary Of Significant Accounting Policies [Line Items]
Net Cash Provided by Operating Activities		80,057	76,203
Effect of exchange rate changes on cash		(416)	(1,746)
Increase in Cash, Cash Equivalents, and Restricted Cash		(1,224)	(4,491)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	7,885	9,109	13,600
Cash, Cash Equivalents, and Restricted Cash, End of Period		7,885	9,109
New Accounting Pronouncement Early Adoption Effect | ASU 2016-18 | As Reported
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		(494)	116
Net Cash Provided by Operating Activities		79,563	76,319
Effect of exchange rate changes on cash		(403)	(1,746)
(Decrease) Increase in Cash and Cash Equivalents		(1,705)	(4,375)
Cash and Cash Equivalents, Beginning Period	$ 6,042	7,747	12,122
Cash and Cash Equivalents, End of Period		$ 6,042	$ 7,747

Contract Receivables - Addition

Contract Receivables - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017
Receivables [Abstract]
Majority of unbilled receivables will be substantially billed and collected	1 year

Contract Receivables - Summary

Contract Receivables - Summary of Contract Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Billed	$ 169,027	$ 168,012
Unbilled	117,037	108,432
Retainages	6,160	5,088
Other	3,144	2,424
Allowance for doubtful accounts	(3,853)	(2,591)
Contract receivables, net	$ 291,515	$ 281,365

Property and Equipment - Proper

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	$ 116,610	$ 114,560
Accumulated depreciation and amortization	(78,558)	(74,076)
Total property and equipment, net	38,052	40,484
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	18,873	17,847
Software and Software Development Costs
Property Plant And Equipment [Line Items]
Property and equipment, gross	42,835	41,269
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	26,076	26,570
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 28,826	$ 28,874

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 17,691	$ 16,638	$ 16,222

Goodwill and Other Intangible53

Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance as of January 1	$ 683,683,000	$ 687,404,000
Effect of foreign currency translation	2,425,000	(4,833,000)
Balance as of December 31	$ 686,108,000	683,683,000
Trade NTE
Goodwill resulting from business combinations		191,000
Mostra
Goodwill resulting from business combinations		654,000
Olson
Goodwill resulting from business combinations		$ 267,000

Goodwill and Other Intangible54

Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amortization of intangible assets	$ 10,888	$ 12,481	$ 17,184
Minimum
Finite-lived intangible asset, useful life	4 years
Maximum
Finite-lived intangible asset, useful life	10 years
Weighted Average
Finite-lived intangible asset, useful life	9 years 1 month 6 days
Weighted Average | Customer Relationships
Finite-lived intangible asset, useful life	9 years 1 month 6 days
Weighted Average | Technology-Based Intangible Assets
Finite-lived intangible asset, useful life	5 years 6 months

Goodwill and Other Intangible55

Goodwill and Other Intangible Assets - Schedule of Other Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite lived intangible assets, gross carrying value	$ 86,341	$ 117,269
Accumulated amortization	(51,132)	(71,235)
Finite lived intangible assets, net carrying value	35,209	46,034
Indefinite lived intangible assets, gross carrying value	95	95
Total intangible assets, gross carrying value	86,436	117,364
Other intangible assets, net	35,304	46,129
Customer-Related Intangible Assets
Finite lived intangible assets, gross carrying value	84,878	115,806
Accumulated amortization	(49,782)	(70,090)
Finite lived intangible assets, net carrying value	35,096	45,716
Developed Technology Rights
Finite lived intangible assets, gross carrying value	1,463	1,463
Accumulated amortization	(1,350)	(1,145)
Finite lived intangible assets, net carrying value	$ 113	$ 318

Goodwill and Other Intangible56

Goodwill and Other Intangible Assets - Schedule of Estimated Future Amortization Expense Relating to Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
2,018	$ 8,441
2,019	6,132
2,020	4,532
2,021	4,082
2,022	4,125
Thereafter	7,897
Finite lived intangible assets, net carrying value	$ 35,209	$ 46,034

Accrued Salaries and Benefits -

Accrued Salaries and Benefits - Schedule of Accrued Salaries and Benefits (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Employee Related Liabilities Current [Abstract]
Accrued paid time off and leave	$ 11,904	$ 11,342
Accrued salaries	9,343	9,443
Accrued bonuses, liability-classified awards and commissions	16,909	13,025
Accrued payroll taxes and withholdings	2,557	1,948
Accrued medical	3,720	3,026
Other	1,212	979
Total accrued salaries and benefits	$ 45,645	$ 39,763

Accrued Expenses and Other Cu58

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued subcontractor and other direct costs	$ 47,508	$ 30,153
Deposits	6,641	12,389
Accrued IT and software licensing costs	2,261	5,349
Accrued taxes and insurance premiums	1,963	1,306
Accrued lease exit and facilities costs	1,591	77
Accrued interest	705	841
Accrued professional services	1,131	795
Other accrued expenses and current liabilities	3,280	1,721
Total accrued expenses and other current liabilities	$ 65,080	$ 52,631

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details)	May 11, 2017USD ($)Bank	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Credit facility syndication, number of commercial banks | Bank	11
Line of credit facility, expiration date		May 17, 2022
Line of credit facility, maximum borrowing capacity without borrowing base requirement	$ 600,000,000
Line of credit facility, accordion feature, additional revolving credit commitments under existing loan facility	300,000,000
New syndicated borrowings used to pay off or pay down borrowings from syndicate members	106,000,000
Line of credit facility, maximum borrowing capacity	$ 60,000,000
Line of credit facility, interest coverage ratio covenant	300.00%
Line of credit facility, leverage ratio covenant	375.00%
Line of credit facility, interest rate during period		0.15%	0.25%
Line of credit facility, remaining borrowing capacity		$ 390,000,000
Line of credit facility, current borrowing capacity		245,100,000
Debt issuance costs, net		6,900,000	$ 5,800,000
Accumulated amortization, debt issuance costs		4,700,000	4,500,000
Amortization of debt issuance costs		673,000	$ 532,000	$ 532,000
Debt issuance costs		$ 1,612,000		$ 17,000
Number of letters of credit, outstanding		12	9
Letters of credit outstanding, amount		$ 3,700,000	$ 3,400,000
Minimum
Debt Instrument [Line Items]
Line of Credit Facility, Committement Fee Unused Capacity		0.13%
Maximum
Debt Instrument [Line Items]
Line of Credit Facility, Committement Fee Unused Capacity		0.25%
Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.50%
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.25%
London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		1.00%
London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate		2.00%

Long-Term Debt - Schedule of Lo

Long-Term Debt - Schedule of Long-Term Debt Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt Outstanding	$ 206,250	$ 259,389
Line of Credit
Debt Instrument [Line Items]
Debt Outstanding	$ 206,250	$ 259,389
Weighted Average Interest Rate	2.65%	2.46%

Derivative Instruments and He61

Derivative Instruments and Hedging Activities - Additional Information (Details) - USD ($)	Aug. 31, 2017	Sep. 30, 2016	Dec. 31, 2017
Derivative [Line Items]
Net amount of realized gains and losses from hedge agreements			$ 700,000
Interest Rate Swap | Cash Flow Hedging | Designated as Hedging Instrument
Derivative [Line Items]
Aggregate notional amount	$ 25,000,000	$ 100,000,000
Derivative, Fixed Interest Rate	1.8475%
Beginning date of transaction	Aug. 31, 2018	Jan. 31, 2018
Derivative, maturity date	Aug. 31, 2023	Jan. 31, 2023

Income Taxes - Income Before In

Income Taxes - Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 69,347	$ 69,159	$ 54,150
Foreign	4,639	5,348	9,450
Income before income taxes	$ 73,986	$ 74,507	$ 63,600

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 12,995	$ 12,979	$ 14,797
State	3,243	3,514	2,669
Foreign	1,476	1,932	1,475
Total current	17,714	18,425	18,941
Deferred:
Federal	(9,425)	8,872	4,562
State	2,749	1,222	512
Foreign	72	(596)	216
Total deferred	(6,604)	9,498	5,290
Income tax expense	$ 11,110	$ 27,923	$ 24,231

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred Tax Assets
Allowance for bad debt	$ 1,003	$ 1,008
Accrued paid time off	1,624	2,592
Accrued bonus		55
Foreign net operating loss (NOL) carry forward	1,301	1,371
Federal/state net operating loss (NOL) carry forward	507	3,010
Stock option compensation	2,726	4,292
Deferred rent	3,355	5,423
Deferred compensation	3,238	3,662
Foreign tax credits	505	2,631
Foreign exchange	2,051	5,349
Accrued liabilities and other	3,272	3,378
Deferred Tax Assets, gross, before valuation allowance	21,367	34,780
Less: Valuation Allowance	(1,636)	(1,131)	$ (933)	$ (542)
Total Deferred Tax Assets	19,731	33,649
Deferred Tax Liabilities
Retention	(1,375)	(1,684)
Prepaid expenses	(1,045)	(1,654)
Payroll taxes	(489)	(617)
Unbilled revenue	(5,407)	(8,728)
Depreciation	(4,773)	(6,664)
Amortization	(39,993)	(51,842)
Deferred gain and other		(1,574)
Total Deferred Tax Liabilities	(53,082)	(72,763)
Total Net Deferred Tax Liability	(33,351)	(39,114)
State and Local Jurisdiction
Deferred Tax Assets
Tax credits	$ 1,785	1,784
United States Government
Deferred Tax Assets
Tax credits		$ 225

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Income tax rate		35.00%	35.00%	35.00%
Provisional net tax benefit on re-measurement of deferred tax balances		$ 17,600,000
Provisional estimate of one-time transition tax liability for foreign subsidiaries, net of related foreign tax credits		1,400,000
Additional income taxes for remaining undistributed foreign earnings not subject to transition tax		$ 0
Operating loss carryforwards expiration term		20 years
Deferred tax assets, valuation allowance		$ 1,636,000	$ 1,131,000	$ 933,000	$ 542,000
Valuation allowance, deferred tax asset, increase (decrease), amount		505,000	198,000	391,000
Unrecognized tax benefits		820,000	1,185,000	$ 400,000	$ 702,000
Unrecognized tax benefits that would impact effective tax rate		700,000	1,000,000
Unrecognized tax benefits, income tax penalties and interest accrued		200,000	200,000
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit		$ 700,000
Earliest Tax Year | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax year		2,013
Earliest Tax Year | State and Foreign Jurisdictions
Income Taxes [Line Items]
Open tax year		2,013
Latest Tax Year | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax year		2,016
Latest Tax Year | State and Foreign Jurisdictions
Income Taxes [Line Items]
Open tax year		2,016
Foreign Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards		$ 4,100,000	4,100,000
Deferred tax assets, valuation allowance		1,100,000	1,100,000
Valuation allowance, deferred tax asset, increase (decrease), amount		500,000
Domestic Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards		$ 8,500,000
Net operating loss carry-forwards, expiration year		2,034
State and Local Jurisdiction
Income Taxes [Line Items]
Tax credit carry-forward, amount		$ 2,800,000
Deferred tax assets, tax credit carry-forwards		$ 1,785,000	$ 1,784,000
State and Local Jurisdiction | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carry-forwards, expiration year		2,017
State and Local Jurisdiction | Latest Tax Year
Income Taxes [Line Items]
Tax credit carry-forwards, expiration year		2,026
Scenario, Forecast
Income Taxes [Line Items]
Income tax rate	21.00%

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefit Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, beginning balance	$ 1,185	$ 400	$ 702
Decrease attributable to settlements			(174)
Increase attributable to tax positions taken during a prior period		925	12
Decrease attributable to lapse of statute of limitations	(365)	(140)	(140)
Unrecognized tax benefits, ending balance	$ 820	$ 1,185	$ 400

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Taxes at statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	4.40%	3.90%	3.90%
Foreign tax rate differential	(0.30%)	(0.10%)	(0.30%)
Tax legislation	(22.60%)
Other permanent differences	0.70%	0.80%	1.90%
Prior year tax adjustments	(0.30%)	(1.00%)	(1.90%)
Unrecognized tax benefits	0.10%	1.00%
Valuation allowance	0.70%	(0.30%)
Equity-based compensation	(2.10%)	(1.00%)
Tax credits	(0.60%)	(0.80%)	(0.50%)
Taxes at effective rate	15.00%	37.50%	38.10%

Accumulated Other Comprehensi68

Accumulated Other Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Foreign currency translation adjustments		$ 7,638	$ 11,815
Gain on sale of interest rate hedge agreement	[1]	(2,158)	(2,175)
Change in fair value on derivative designated as cash flow hedge	[2]	(441)
Total		$ 5,039	$ 9,640
[1]	Represents the fair value of an interest rate hedge agreement, designated as a cash flow hedge, which was sold on December 1, 2016. The fair value of the interest rate hedge agreement was recorded in other comprehensive income, net of tax, and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from January 31, 2018 to January 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.
[2]	Represents the change in fair value of an interest rate hedge agreement designated as a cash flow hedge, and entered into on August 31, 2017. The fair value of the interest rate hedge agreement was recorded in other comprehensive income and will be reclassified to earnings when earnings are impacted by the hedged items, as interest payments are made on the Credit Facility from August 31, 2018 to August 31, 2023. See additional details of the hedge agreement in Note 9—Derivative Instruments and Hedging Activities.

Restricted Cash - Reconciliatio

Restricted Cash - Reconciliation of Cash and Cash Equivalents, and Restricted Cash to the Total Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents		$ 11,809	$ 6,042	$ 7,747	$ 12,122
Restricted cash - current	[1]	11,191
Restricted cash - non-current		1,266	1,843	1,362	1,478
Total cash, cash equivalents, and restricted cash shown in the consolidated statement of cash flows		$ 24,266	$ 7,885	$ 9,109	$ 13,600
[1]	Restricted cash – current for the year ended December 31, 2017 represents amounts held in an escrow account for a future acquisition. See Note 19 – Subsequent Events.

Accounting for Stock-based Co70

Accounting for Stock-based Compensation - Additional Information (Details)	Jun. 05, 2015shares	Mar. 31, 2015PerformancePeriod	Dec. 31, 2017USD ($)PerformancePeriod$ / sharesshares	Dec. 31, 2016USD ($)PerformancePeriodshares	Dec. 31, 2015USD ($)PerformancePeriodshares	Jun. 04, 2015shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, weighted average remaining contractual term			5 years
Performance based share awards, performance period			3 years
Share-based compensation arrangement by share-based payment award, options, vested in period, fair value | $			$ 1,900,000	$ 1,300,000	$ 2,000,000
Share-based compensation arrangement by share-based payment award, options, vested and expected to vest, exercisable, weighted average remaining contractual term			5 years
Share-based compensation arrangement by share-based payment award, options, exercisable, weighted average remaining contractual term			5 years
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected forfeiture rate			1.86%
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected forfeiture rate			19.51%
Options, Restricted Stock and RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant | shares	5,966,186
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, weighted average remaining contractual term			10 years
Share-based compensation arrangement by share-based payment award, options, grants in period, gross | shares			0	0	0
Share price | $ / shares			$ 52.50
Share-based compensation arrangement by share-based payment award, options, exercises in period, intrinsic value | $			$ 4,500,000	$ 2,500,000	$ 800,000
Employee Stock Option | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance based share awards, performance period			3 years
Employee Stock Option | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance based share awards, performance period			4 years
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share price | $ / shares			$ 52.50
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value | $			$ 6,300,000	7,200,000	6,300,000
Restricted Stock Units (RSUs) | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance based share awards, performance period			3 years
Restricted Stock Units (RSUs) | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance based share awards, performance period			4 years
Cash Settled RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Performance based share awards, performance period			4 years
Share price | $ / shares			$ 52.50
Share-based compensation arrangement by share-based payment award, equity instruments other than options, vested in period, fair value | $			$ 6,900,000	$ 5,900,000	$ 2,900,000
Non-Employee Director Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee service share-based compensation, nonvested awards, compensation not yet recognized, share-based awards other than options | $			$ 0
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share price | $ / shares			$ 52.50
Number of performance period in performance based share program | PerformancePeriod		2	1	2	3
Percentage of multiplication award by product			2.00%
Share-based compensation arrangement by share-based payment award, fair value assumptions, expected dividend rate			0.00%	0.00%	0.00%
Share-based compensation arrangement by share-based payment award, fair Value assumptions, expected volatility rate			31.30%	30.90%	29.30%
Share-based compensation arrangement by share-based payment award, fair value assumptions, risk free interest rate			1.50%	1.00%	1.00%
Omnibus Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of additional shares authorized | shares	1,540,000
Share-based compensation arrangement by share-based payment award, number of shares authorized | shares	5,090,000					3,550,000
Share-based compensation arrangement by share-based payment award, number of shares available for grant | shares			1,900,000
Equivalent share deducted for every one share delivered	1.93

Accounting for Stock-based Co71

Accounting for Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 17,544	$ 15,943	$ 14,741
Stock-Based Compensation Unrecognized	29,298
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 164	909	1,546
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	0 years
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 7,080	6,325	7,409
Stock-Based Compensation Unrecognized	$ 12,659
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 10 months 24 days
Cash Settled RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 7,253	7,091	4,414
Stock-Based Compensation Unrecognized	$ 13,922
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 10 months 24 days
Non-Employee Director Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 671	741	645
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	0 years
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-Based Compensation Recognized	$ 2,376	$ 877	$ 727
Stock-Based Compensation Unrecognized	$ 2,717
Stock-Based Compensation Unrecognized Weighted- Average Period to Recognize (Year)	1 year 6 months

Accounting for Stock-based Co72

Accounting for Stock-based Compensation - Outstanding Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding Ending Balance	411,498
Number of Shares, Exercisable at December 31, 2017	411,498
Weighted Average Exercise Price, Outstanding Ending Balance	$ 30.71
Weighted Average Exercise Price, Exercisable at December 31, 2017	$ 30.71
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding Beginning Balance	587,407	723,005	766,924
Number of Shares, Exercised	(175,909)	(128,301)	(43,919)
Number of Shares, Granted	0	0	0
Number of Shares, Forfeited/Expired		(7,297)
Number of Shares, Outstanding Ending Balance	411,498	587,407	723,005
Number of Shares, Vested plus expected to vest at December 31, 2017	411,498
Number of Shares, Exercisable at December 31, 2017	411,498
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 29.56	$ 28.62	$ 28.20
Weighted Average Exercise Price, Exercised	26.84	23.65	21.23
Weighted Average Exercise Price, Forfeited/Expired		40.68
Weighted Average Exercise Price, Outstanding Ending Balance	30.71	$ 29.56	$ 28.62
Weighted Average Exercise Price, Vested plus expected to vest at December 31, 2017	30.71
Weighted Average Exercise Price, Exercisable at December 31, 2017	$ 30.71
Aggregate Intrinsic Value, Outstanding at December 31,2017	$ 8,965
Aggregate Intrinsic Value, Vested plus expected to vest at December 31, 2017	8,965
Aggregate Intrinsic Value, Exercisable at December 31, 2017	$ 8,965

Accounting for Stock-based Co73

Accounting for Stock-based Compensation - Stock Options Outstanding by Exercise Price Range (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower range	$ 21.77
Range of Exercise Prices, Upper range	$ 41
Number Outstanding | shares	411,498
Weighted Average Remaining Contractual Term	5 years
Weighted Average Exercise Price	$ 30.71
Number Exercisable | shares	411,498
Weighted Average Exercise Price	$ 30.71
Price Range 1
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower range	21.77
Range of Exercise Prices, Upper range	$ 25
Number Outstanding | shares	62,917
Weighted Average Remaining Contractual Term	3 years 3 months 18 days
Weighted Average Exercise Price	$ 21.77
Number Exercisable | shares	62,917
Weighted Average Exercise Price	$ 21.77
Price Range 2
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower range	25.01
Range of Exercise Prices, Upper range	$ 28
Number Outstanding | shares	205,332
Weighted Average Remaining Contractual Term	4 years 9 months 18 days
Weighted Average Exercise Price	$ 26.50
Number Exercisable | shares	205,332
Weighted Average Exercise Price	$ 26.50
Price Range 3
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices, Lower range	28.01
Range of Exercise Prices, Upper range	$ 40.68
Number Outstanding | shares	143,249
Weighted Average Remaining Contractual Term	6 years 1 month 6 days
Weighted Average Exercise Price	$ 40.68
Number Exercisable | shares	143,249
Weighted Average Exercise Price	$ 40.68

Accounting for Stock-based Co74

Accounting for Stock-based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Non-vested Beginning Balance	507,998	555,904	643,887
Number of Shares, Granted	194,227	240,868	250,159
Number of Shares, Vested	(179,974)	(221,659)	(233,899)
Number of Shares, Cancelled	(58,664)	(67,115)	(104,243)
Number of Shares, Non-vested Ending Balance	463,587	507,998	555,904
Number of Shares, expected to vest in the future	463,587
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance	$ 36.12	$ 35.40	$ 31.10
Weighted-Average Grant Date Fair Value, Granted	41.41	34.68	39.04
Weighted-Average Grant Date Fair Value, Vested	35.19	32.45	26.85
Weighted-Average Grant Date Fair Value, Cancelled	36.04	37.60	36.76
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance	38.71	$ 36.12	$ 35.40
Weighted-Average Grant Date Fair Value, expected to vest in the future	$ 38.71
Aggregate Intrinsic Value, Non-vested	$ 24,338
Aggregate Intrinsic Value, expected to vest in the future	$ 24,338

Accounting for Stock-based Co75

Accounting for Stock-based Compensation - Cash-settled Restricted Stock Unit Activity (Details) - Cash Settled RSUs [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Non-vested Beginning Balance	463,022	446,663	537,119
Number of Shares, Granted	174,419	233,790	121,015
Number of Shares, Vested	(161,576)	(146,619)	(78,033)
Number of Shares, Cancelled	(83,949)	(70,812)	(133,438)
Number of Shares, Non-vested Ending Balance	391,916	463,022	446,663
Number of Shares, expected to vest in the future	391,916
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance	$ 35.96	$ 37.18	$ 36.36
Weighted-Average Grant Date Fair Value, Granted	42.06	34.29	39.35
Weighted-Average Grant Date Fair Value, Vested	40.78	34.70	33.29
Weighted-Average Grant Date Fair Value, Cancelled	36.43	37.55	38.14
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance	38.80	$ 35.96	$ 37.18
Weighted-Average Grant Date Fair Value, expected to vest in the future	$ 38.80
Aggregate Intrinsic Value, Non-vested	$ 20,576,000
Aggregate Intrinsic Value, expected to vest in the future	$ 20,576,000

Accounting for Stock-based Co76

Accounting for Stock-based Compensation - Summary of Non-employee Director Awards Granted (Details) - Non-Employee Director Awards - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted	13,861	15,299	18,109
Weighted- Average Grant Date Fair Value	$ 48.41	$ 39.32	$ 35.62

Accounting for Stock-based Co77

Accounting for Stock-based Compensation - Summary of Performance Shares Activity (Details) - Performance Shares - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number ofShares
Number of Shares, Non-vested Beginning Balance	129,974	58,822
Number of Shares, Granted	60,929	74,574	58,822
Number of Shares, Cancelled	(3,881)	(3,422)
Number of Shares, Non-vested Ending Balance	187,022	129,974	58,822
Number of Shares, expected to vest in the future	126,846
Weighted-Average Grant Date Fair Value
Weighted-Average Grant Date Fair Value, Non-vested Beginning Balance	$ 40.57	$ 44.21
Weighted-Average Grant Date Fair Value, Granted	38.81	37.75	$ 44.21
Weighted-Average Grant Date Fair Value, Cancelled	42.83	41.61
Weighted-Average Grant Date Fair Value, Non-vested Ending Balance	39.95	$ 40.57	$ 44.21
Weighted-Average Grant Date Fair Value, expected to vest in the future	$ 38.09
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Non-vested	$ 9,819
Aggregate Intrinsic Value, expected to vest in the future	$ 6,659

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	142	163,564	167,849

Earnings Per Share - Schedule o

Earnings Per Share - Schedule of Dilutive Effect of Stock Options RSUs and PSAs (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	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Basic weighted-average shares outstanding	18,646	18,666	18,775	18,972	18,988	18,965	19,008	18,994		18,766,000	18,989,000	19,335,000
Effect of potential exercise of stock options, RSUs, and performance shares										478,000	427,000	328,000
Diluted weighted-average shares outstanding	19,136	19,024	19,086	19,423	19,512	19,329	19,293	19,273		19,244,000	19,416,000	19,663,000
[1]	Includes adjustments for the adoption ASU 2016-09 in the second quarter of 2016.

Share Repurchase Program - Addi

Share Repurchase Program - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017USD ($)shares	Nov. 04, 2017USD ($)
Equity [Abstract]
Stock repurchase program, authorized amount	$ 75,000,000	$ 100,000,000
Line of credit facility, conditions for the elimination of limits on shares repurchases, leverage ratio	3.25
Stock Repurchased During Period, Shares | shares	684,335
Stock Repurchased During Period, Value	$ 30,700,000
Stock repurchase program, remaining authorized repurchase amount	$ 100,000,000

Fair Value - Additional Informa

Fair Value - Additional Information (Details) - Level 3 - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, measured at fair value on recurring basis	$ 0	$ 0
Liabilities, measured at fair value on recurring basis	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands	Aug. 31, 2017	Jun. 10, 2017USD ($)	Dec. 31, 2017USD ($)a	Mar. 08, 2010ft²
Loss Contingencies [Line Items]
Community development related to claim			$ 220,200
Operating Leases, Future Minimum Payments Due			193,770
Minimum future sublease rentals			$ 1,400
Corporate Office Lease
Loss Contingencies [Line Items]
Operating Lease, Area of Leased Space | ft²				258,000
Operating Lease, Additional Area of Leased Space | a			72,000
Monthly Rent			$ 900
Percentage of Annual Escalations of Lease Rent			2.50%
Operating Leases, Future Minimum Payments Due			$ 150,600
Term of Lease	12 years
OCD vs ICF Emergency
Loss Contingencies [Line Items]
Loss contingency damages sought value		$ 200,800
Road Home Contract
Loss Contingencies [Line Items]
Contract term, period		3 years
Contract award, value		$ 912,000

Commitments and Contingencies83

Commitments and Contingencies - Future Minimum Rental Payments (Details) $ in Thousands	Dec. 31, 2017USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2,018	$ 36,238
2,019	34,223
2,020	31,459
2,021	31,091
2,022	29,761
Thereafter	30,998
Total	$ 193,770

Commitments and Contingencies84

Commitments and Contingencies - Operating Lease Rent Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases Rent Expense [Abstract]
Rent	$ 36,269	$ 39,537	$ 40,009
Sublease income	(142)	(147)	(32)
Total rent expense	$ 36,127	$ 39,390	$ 39,977

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Maximum defer of compensation subject to statutory limitations, percentage	70.00%
Percentage of employer matching contributions condition, one	100.00%
Percentage of employee entitled to employer matching contribution condition, one	3.00%
Percentage of employer matching contributions condition, two	50.00%
Percentage of employee entitled to employer matching contribution condition, two	2.00%
Defined contribution plan, employer discretionary contribution amount	$ 15,100,000	$ 14,900,000	$ 13,100,000
Deferred compensation arrangement with individual, cash awards granted, percentage	80.00%
Deferred compensation on performance bonuses that eligible employee, percentage	100.00%
Defined contribution plan, employers matching contribution, annual vesting percentage	100.00%
Employee stock purchase plan shares authorized	1,000,000
Employee stock purchase plan annual maximum payroll deduction	$ 25,000
Share-based compensation arrangement by share-based payment award, discount from market price, purchase date	5.00%
Stock issued during period, shares, employee stock purchase plans	27,285
Stock issued during period, value, employee stock purchase plans, per share	$ 47.34
Employee stock purchase plan, number of shares available for grant	724,826

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Subsequent Event	Feb. 27, 2018$ / shares
Subsequent Event [Line Items]
Dividend declaration date	Feb. 27, 2018
Cash dividend per share	$ 0.14
Dividend payment date	Apr. 16, 2018
Dividend close of record date	Mar. 30, 2018

Supplemental Information - Sche

Supplemental Information - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance For Doubtful Accounts Receivable Rollforward
Balance at beginning of period	$ 2,591	$ 2,138	$ 1,887
Bad debt expense	1,480	1,089	268
Write-offs, net of recoveries	(219)	(635)	(8)
Effect of foreign currency translation	1	(1)	(9)
Balance at end of period	$ 3,853	$ 2,591	$ 2,138

Supplemental Information - Sc88

Supplemental Information - Schedule of Income Tax Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation Allowance [Abstract]
Balance at beginning of period	$ 1,131	$ 933	$ 542
Provision for income taxes - valuation allowance	505	198	391
Balance at end of period	$ 1,636	$ 1,131	$ 933

Selected Quarterly Financial 89

Selected Quarterly Financial Data (Unaudited)- Quarterly Financial Data (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	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 321,174	$ 305,301	$ 306,392	$ 296,295	$ 289,559	$ 306,520	$ 305,419	$ 283,599		$ 1,229,162	$ 1,185,097	$ 1,132,232
Operating income	20,181	23,396	22,208	16,633	21,965	23,776	19,358	17,694		82,418	82,793	75,231
Net income	$ 27,070	$ 13,692	$ 11,937	$ 10,177	$ 12,673	$ 13,437	$ 10,583	$ 9,891		$ 62,876	$ 46,584	$ 39,369
Earnings per share:
Basic	$ 1.45	$ 0.73	$ 0.64	$ 0.54	$ 0.67	$ 0.71	$ 0.56	$ 0.52		$ 3.35	$ 2.45	$ 2.04
Diluted	$ 1.41	$ 0.72	$ 0.63	$ 0.52	$ 0.65	$ 0.70	$ 0.55	$ 0.51		$ 3.27	$ 2.40	$ 2
Weighted-average common shares outstanding (in thousands)
Basic	18,646	18,666	18,775	18,972	18,988	18,965	19,008	18,994		18,766,000	18,989,000	19,335,000
Diluted	19,136	19,024	19,086	19,423	19,512	19,329	19,293	19,273		19,244,000	19,416,000	19,663,000
[1]	Includes adjustments for the adoption ASU 2016-09 in the second quarter of 2016.