CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 1,347,387	$ 1,303,937	$ 1,253,646
Direct costs	952,349	917,450	878,049
Gross profit	395,038	386,487	375,597
Selling, general and administrative expenses	314,167	307,250	308,313
Depreciation and amortization	6,050	6,836	7,266
Income from operations	74,821	72,401	60,018
Other expense, net	3,425	4,521	5,100
Income from continuing operations, before income taxes	71,396	67,880	54,918
Income tax expense	16,830	17,004	25,324
Income from continuing operations	54,566	50,876	29,594
Income from discontinued operations, net of tax	76,296	7,104	3,691
Net income	130,862	57,980	33,285
Other comprehensive (loss) income:
Defined benefit pension plans, net of tax	(2,183)	881	(373)
Change in fair value of interest rate swap, net of tax	(807)
Change in fair value of interest rate swap, net of tax		315	289
Comprehensive income	$ 127,872	$ 59,176	$ 33,201
Earnings per share - basic:
Continuing operations (in dollars per share)	$ 2.35	$ 2.05	$ 1.17
Discontinued operations (in dollars per share)	3.29	0.29	0.15
Earnings per share – basic (in dollars per share)	5.64	2.34	1.32
Earnings per share - diluted:
Continuing operations (in dollars per share)	2.29	2.02	1.16
Discontinued operations (in dollars per share)	3.21	0.28	0.14
Earnings per share – diluted (in dollars per share)	$ 5.50	$ 2.30	$ 1.30
Weighted average shares outstanding - basic (in shares)	23,186	24,738	25,222
Weighted average shares outstanding – diluted (in shares)	23,772	25,251	25,586