Loans Held for Sale - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended				1 Months Ended		9 Months Ended		3 Months Ended
	Jun. 30, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2013 Minimum [Member]	Jun. 30, 2013 Maximum [Member]	Sep. 30, 2013 Commercial and Commercial Real Estate [Member]	Sep. 30, 2012 Commercial and Commercial Real Estate [Member]	Sep. 30, 2013 Residential Real Estate [Member]
Servicing Assets at Fair Value [Line Items]
Residential loans held for sale, at fair value		$ 7,918,000		$ 12,591,000	$ 9,911,000
Commercial and residential real estate loans reclassified value held for sale										96,900,000
Proceeds from held for sale										96,900,000
Finance leases held for sale	11,600,000		11,600,000					0	0	0
Loss recognized due to transfer of leases			200,000
Average maturity of portfolio of leases held for sale	2 years 8 months 12 days
Interest rate on portfolio of leases held for sale						3.57%	10.22%
Additional loss from sale of leases held for sale		0
Commercial and commercial real estate loans held for investment								5,900,000	1,600,000
Purchased impaired loans								400,000	1,500,000
Proceeds from sale of loans								7,100,000	2,300,000
Charge-offs								200,000	100,000
Other noninterest income								1,000,000
Income recognized on sale of loans								$ 400,000	$ 800,000