Allowance for Loan Losses - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Jul. 01, 2006
Receivables [Abstract]
Troubled Debt Restructuring		$ 4.5
Criteria for loans to be considered as nonperforming	90 days
Tier One of Government Guarantee				97.00%
Ffelp Loans Net		$ 853
Percentage of FFELP Rehabilitation Loans		62.70%	62.90%