Variable Interest Entities - Schedule of Carrying Value of the Assets and Liabilities Eliminated from Financial Statement Related to the CUSO (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Variable Interest Entity [Line Items]
Prepaid expenses and other current assets	$ (77,571)	$ (57,923)	$ (48,478)
Total assets	(732,149)	(752,838)	(771,113)
Other current liabilities	(58,436)	(27,153)	(27,732)
Total liabilities	(580,518)	(610,766)	(645,185)
CUSO [Member]
Variable Interest Entity [Line Items]
Total assets	(23,152)	(26,606)	(30,136)
Other current liabilities	(302)	(179)	(624)
Other liabilities	(2,487)	(1,073)	(1,940)
Total liabilities	$ (114,360)	$ (122,259)	(125,106)
Consolidation, Eliminations [Member] | CUSO [Member]
Variable Interest Entity [Line Items]
Prepaid expenses and other current assets			3,260
Total assets			3,260
Other current liabilities			23,887
Other liabilities			90,974
Total liabilities			$ 114,861