Variable Interest Entities - Schedule of Carrying Value of the Assets and Liabilities Eliminated from Financial Statement Related to the CUSO (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Variable Interest Entity [Line Items]
Prepaid expenses and other current assets	$ (57,923)	$ (28,400)
Total assets	(749,160)	(806,851)
Other current liabilities	(27,050)	(42,136)
Total liabilities	(601,155)	(691,205)
CUSO [Member]
Variable Interest Entity [Line Items]
Total assets	(26,606)		(30,136)
Other current liabilities	(179)		(624)
Other liabilities	(1,073)		(1,940)
Total liabilities	(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