Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities
Net income	$ 54,959	$ 68,938	$ 61,400
Adjustments to reconcile net income to net cash provided by operating activities:
Bad debt expense	4,062	624	2,480
Deferred income taxes	(1,865)	(123)	5,100
Non-cash equity compensation	17,555	15,818	11,506
Depreciation and amortization	33,748	28,182	27,206
Non-cash lease expense	(2,307)	(1,247)	523
Facilities consolidation reserve	(288)	(274)	(260)
Remeasurement of contingent acquisition liability			505
Amortization of debt issuance costs	710	507	510
Impairment of long-lived assets	3,090	1,728
Other adjustments, net	964	181	449
Changes in operating assets and liabilities, net of the effect of acquisitions:
Net contract assets and liabilities	6,064	(11,963)	(14,148)
Contract receivables	54,384	(31,300)	(60,096)
Prepaid expenses and other assets	(5,410)	1,997	(6,650)
Accounts payable	(51,177)	31,949	28,309
Accrued salaries and benefits	26,810	8,012	(2,159)
Accrued subcontractors and other direct costs	32,544	(12,293)	10,762
Accrued expenses and other current liabilities	(18,198)	(4,951)	11,120
Income tax receivable and payable	5,375	(4,489)	(2,063)
Other liabilities	12,125	144	176
Net Cash Provided by Operating Activities	173,145	91,440	74,670
Cash Flows from Investing Activities
Capital expenditures for property and equipment and capitalized software	(17,683)	(26,901)	(21,812)
Payments for business acquisitions, net of cash acquired	(253,265)	(3,569)	(34,575)
Net Cash Used in Investing Activities	(270,948)	(30,470)	(56,387)
Cash Flows from Financing Activities
Advances from working capital facilities	1,020,451	686,830	573,991
Payments on working capital facilities	(870,114)	(721,809)	(579,817)
Payments on capital expenditure obligations	(1,712)	(1,621)	(3,726)
Receipt of restricted contract funds	65,694
Payment of restricted contract funds	(106)
Debt issue costs	(2,094)		(21)
Proceeds from exercise of options	37	2,914	5,842
Dividends paid	(10,551)	(10,540)	(7,915)
Net payments for stockholder issuances and buybacks	(29,726)	(23,414)	(17,125)
Payments on business acquisition liabilities	1,924
Net Cash Provided by (Used in) Financing Activities	169,955	(67,640)	(28,771)
Effect of Exchange Rate Changes on Cash, Cash Equivalents, and Restricted Cash	3,353	166	(792)
Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	75,505	(6,504)	(11,280)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	6,482	12,986	24,266
Cash, Cash Equivalents, and Restricted Cash, End of Period	81,987	6,482	12,986
Supplemental disclosure of cash flow information:
Interest	14,337	10,424	9,893
Income taxes	15,954	$ 26,595	14,870
Non-cash investing and financing transactions:
Deferred and contingent consideration arising from businesses acquired			8,391
Capital expenditure obligations			$ 6,121
Tenant improvements funded by lessor	3,124
Exercise of options receivable from shareholders	$ 2,615