Quarterly Financial Data (Unaudited) - Summary of Quarterly Financial Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Net service revenues	$ 318,739	$ 313,810	$ 302,758	$ 282,024	$ 282,061	$ 279,956	$ 264,720	$ 246,991	$ 1,217,331	$ 1,073,728	$ 1,005,487
Gross profit	98,378	98,291	94,386	83,526	89,371	91,055	86,595	77,355	374,581	344,376	320,586
(Loss) income from continuing operations, net of income taxes	9,061	7,995	7,953	4,389	(9,714)	7,636	5,443	1,929	29,398	5,294	(42,131)
Income (loss) from discontinued operations, net of income taxes	(116)	57,023	2,750	1,860	1,480	1,343	1,505	1,165	61,517	5,493	28,428
Net income (loss)	$ 8,945	$ 65,018	$ 10,703	$ 6,249	$ (8,234)	$ 8,979	$ 6,948	$ 3,094	$ 90,915	$ 10,787	$ (13,703)
Earnings (loss) per share-basic	$ 0.30	$ 2.07	$ 0.33	$ 0.19	$ (0.25)	$ 0.27	$ 0.21	$ 0.09	$ 2.89	$ 0.32	$ (0.38)
Earnings (loss) per share-diluted	$ 0.30	$ 2.06	$ 0.33	$ 0.19	$ (0.25)	$ 0.27	$ 0.21	$ 0.09	$ 2.87	$ 0.32	$ (0.38)