Schedule of Quarterly Financial Data (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 Data [Line Items]
Revenues	$ 425,158	$ 451,178	$ 454,324	$ 425,552	$ 415,998	$ 414,643	$ 414,613	$ 407,178	$ 1,756,212	$ 1,652,432	$ 1,576,871
Direct cost of revenues	281,689	293,244	295,549	274,275	268,901	255,152	259,528	258,480	1,144,757	1,042,061	980,532
Selling, general and administrative expenses	115,965	102,461	107,032	108,387	107,196	94,513	96,325	96,647	433,845	394,681	378,016
Special charges	1,628	5,347	9,364		27,568	10,419		427	16,339	38,414	29,557
Acquisition-related contingent consideration	(85)	257	(5)	(1,843)	(4,778)	630	(7,452)	731	(1,676)	(10,869)	(3,064)
Amortization of other intangible assets	4,055	3,398	3,452	4,616	5,661	5,776	5,953	5,564	15,521	22,954	22,407
Goodwill impairment charge						83,752				83,752	110,387
Costs and Expenses	403,252	404,707	415,392	385,435	404,548	450,242	354,354	361,849	1,608,786	1,570,993	1,517,835
Operating income (loss)	21,906	46,471	38,932	40,117	11,450	(35,599)	60,259	45,329	147,426	81,439	59,036
Interest income and other	1,205	1,014	1,448	1,003	46	1,152	(387)	937	4,670	1,748	5,659
Interest expense	(12,488)	(12,634)	(12,908)	(12,655)	(12,776)	(12,814)	(13,071)	(12,715)	(50,685)	(51,376)	(56,731)
Income (loss) before income tax provision	10,623	34,851	27,472	28,465	(1,280)	(47,261)	46,801	33,551	101,411	31,811	3,114
Income tax provision	9,702	12,329	10,225	10,348	5,859	3,360	23,315	9,871	42,604	42,405	40,100
Net income (loss)	$ 921	$ 22,522	$ 17,247	$ 18,117	$ (7,139)	$ (50,621)	$ 23,486	$ 23,680	$ 58,807	$ (10,594)	$ (36,986)
Earnings (loss) per common share - basic	$ 0.02	$ 0.57	$ 0.43	$ 0.46	$ (0.18)	$ (1.29)	$ 0.60	$ 0.60	$ 1.48	$ (0.27)	$ (0.92)
Earnings (loss) per common share - diluted	$ 0.02	$ 0.55	$ 0.42	$ 0.45	$ (0.18)	$ (1.29)	$ 0.58	$ 0.58	$ 1.44	$ (0.27)	$ (0.92)
Basic	39,991	39,789	39,681	39,438	39,115	39,094	39,143	39,403	39,726	39,188	40,316
Diluted	41,090	40,819	40,750	40,457	39,115	39,094	40,293	40,620	40,729	39,188	40,316