Risks and Uncertainties - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 04, 2014	Sep. 30, 2014
Unusual Risk or Uncertainty [Line Items]
Percentage of cash collateral amount equal to face amount	103.00%
Percentage of cash collateral amount equal to face amount of ED Letter of Credit	109.00%
Cash collateral to be provided for letter of credit as of the filing date	$ 89,300
Payments under PEAK Guarantee			$ 159,300
Payments on Behalf of Borrowers			1,832
CUSO RSA [Member]
Unusual Risk or Uncertainty [Line Items]
Net guarantee obligation payments	4,989	$ 1,158
CUSO RSA [Member] | CUSO [Member]
Unusual Risk or Uncertainty [Line Items]
Net guarantee obligation payments			9,139
Recoveries from charged-off loans			$ 466
2014 [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under PEAKS guarantee	30,000
Payments under CUSO Program	11,600
2014 [Member] | CUSO RSA [Member]
Unusual Risk or Uncertainty [Line Items]
Recoveries from charged-off loans	1,400
2015 [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under PEAKS guarantee	4,200
Payments under CUSO Program	$ 20,900
Minimum [Member]
Unusual Risk or Uncertainty [Line Items]
Percentage of cash collateral amount equal to face amount	103.00%
Percentage of cash collateral amount equal to face amount of ED Letter of Credit	109.00%
Term Loan [Member]
Unusual Risk or Uncertainty [Line Items]
Cash collateral to be provided for letter of credit as of the filing date					$ 100
Aggregate principal amount	$ 100,000			$ 100,000