Reserve for Unfunded Commitments - Summary of the Activity in Reserve for Unfunded Commitments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Commitments And Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 3,210	$ 2,590	$ 3,615	$ 2,740
Change in reserve for unfunded commitments	(335)	(35)	(740)	(185)
Balance at end of period	$ 2,875	$ 2,555	$ 2,875	$ 2,555