Investment Securities - Realized Gains and Losses on Sales of Investment Securities (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Investments, Debt and Equity Securities [Abstract]
Gross gains, Sales transactions	$ 0	$ 1	$ 0	$ 3,381
Gross gains, Maturities and other securities transactions	7	41	8	649
Gross losses, Maturities and other securities transactions	0	(1)	(9)	(31)
Gains (losses) on Maturities and other securities transactions, net	7	40	(1)	618
Total gains on securities transactions, net	$ 7	$ 41	$ (1)	$ 3,999