Restructuring and Excess Facilities - Activities in Restructuring Accrual (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended			3 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2011 Excess Facilities [Member]	Dec. 31, 2010 Excess Facilities [Member]	Dec. 31, 2012 Excess Facilities [Member]	Dec. 31, 2011 Excess Facilities [Member]	Dec. 31, 2010 Excess Facilities [Member]	Dec. 31, 2010 Campus Consolidation [Member]	Dec. 31, 2010 UK Closure [Member]	Dec. 31, 2011 Scopus Facilities [Member]	Dec. 31, 2010 Scopus Facilities [Member]	Dec. 31, 2009 Scopus Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 2,593	$ 2,920	$ 5,332	$ 2,862		$ 2,593	$ 2,862	$ 3,117	$ 1,715	$ 276	$ 58	$ 224
Provisions (recoveries)	94	517	2,991	(517)	(3,061)	94	517	3,061	(2)	(71)		3	(8,300)
Cash payments, net of sublease income	(1,818)	(844)	(5,403)			(1,818)	(786)	(3,316)	(1,713)	(205)	(58)	(169)
Ending Balance	$ 869	$ 2,593	$ 2,920		$ 2,862	$ 869	$ 2,593	$ 2,862				$ 58	$ 224