Commitments and Contingencies - Activity With Respect to Claims and Contingencies (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
CUSO RSA [Member]
Schedule of Claims and Contingencies [Line Items]
Payment recoveries	$ 466	$ 103
Other claims and contingencies [Member]
Schedule of Claims and Contingencies [Line Items]
Payment recoveries	475	574
PEAKS Program Guarantee [Member]
Schedule of Claims and Contingencies [Line Items]
Estimated recoveries	$ 0	$ 1,408