Commitments and Contingencies - Aggregate Amount of Guarantee Payments, Discharge Payments and Payments on Behalf of Borrowers (Detail) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended				12 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014		Dec. 31, 2014
Loss Contingencies [Line Items]
PEAKS Guarantee									$ 159,300
Payments on Behalf of Borrowers									$ 1,832
Total	$ 4,856		$ 54,326		$ 38,406		$ 100,706
PEAKS Program [Member]
Loss Contingencies [Line Items]
PEAKS Guarantee	4,856		52,517		25,313		94,318
Payments on Behalf of Borrowers	0		0		0		1,832
CUSO RSA [Member]
Loss Contingencies [Line Items]
Regular Payments	0	[1]	1,809	[2]	3,840	[3]	4,556	[2]
Discharge Payments	$ 0		$ 0		$ 9,253		$ 0

[1] As described above, we deferred payment of $2,574 of Regular Payments, that otherwise would have been due during this period, to January 2016. In addition, the amount of the recoveries of charged-off loans received by the CUSO during this period that are due but have not been paid to us and that we expect to offset against these Regular Payments was $351.

[2] This amount is net of $156 of recoveries from charged-off loans owed to us that we offset against amounts owed by us under the CUSO RSA.

[3] This amount is net of $521 of recoveries from charged-off loans owed to us that we offset against amounts owed by us under the CUSO RSA. In addition, we deferred payment of $3,402 of Regular Payments, that otherwise would have been due during this period, to January 2016. We also expect to utilize the amount of recoveries of charged-off loans received by the CUSO during this period that has not been paid to us, which totaled approximately $468, to offset against amounts that we expect to pay under the CUSO RSA in January 2016.