Risks and Uncertainties - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2014 USD ($)
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
Letter of credit termination date	Nov. 04, 2019
Outstanding borrowing under Amended Credit Agreement	$ 50,000
Credit Agreement [Member]
Unusual Risk or Uncertainty [Line Items]
Outstanding borrowing under Amended Credit Agreement	50,000
Two Thousand Fourteen [Member] | PEAKS Guarantee [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under PEAKS guarantee	163,239
Two Thousand Fourteen [Member] | 2009 RSA [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under Laon Program	8,610
2015 [Member] | PEAKS Guarantee [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under PEAKS guarantee	9,813
2015 [Member] | 2009 RSA [Member]
Unusual Risk or Uncertainty [Line Items]
Payments under Laon Program	$ 14,251