Debt - Total Amount of Interest Expense and Discount Accretion on PEAKS Senior Debt (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Debt Instrument [Line Items]
Interest expense	$ 10,388	$ 11,812
PEAKS Senior Debt [Member]
Debt Instrument [Line Items]
Interest expense	3,259	11,017
Discount accretion	$ 1,655	$ 6,452