Fair Value - Reconciliation and Income Statement Classification of Gains and Losses for Securities Available for Sale Measure at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Balance at beginning of period	$ 2,950	$ 2,816
Additions to Level 3	263	441
Net unrealized gain (loss) included in other comprehensive income (1)	7,571	1,267
Principal payments	(791)	(1,046)
Recognized impairment charge included in the statement of income (2)	(1,240)	(528)
Transfers out of Level 3	(8,753)
Balance at end of period		$ 2,950