Investment Securities - Roll Forward of Credit Losses on Securities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]
Cumulative credit losses, Beginning Balance	$ 63,114
Additions for credit losses on securities for which OTTI was not previously recognized	1,267
Additions for additional credit losses on securities for which OTTI was previously recognized	6,065
Cumulative credit losses, Ending Balance	$ 70,446