Borrowings - Federal Funds Purchased and Securities Sold Under Agreements to Repurchase (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Debt Disclosure [Abstract]
Maximum amount outstanding at any month end	$ 165,770	$ 149,316	$ 154,440
Weighted average interest rate at end of year	0.17%	0.21%	0.22%
Average amount outstanding	$ 155,222	$ 141,592	$ 106,495
Weighted average interest rate during the year	0.18%	0.24%	0.26%