Goodwill and Intangibles - Summary of Other Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Gross Intangible Assets	$ 8,873	$ 8,834
Accumulated Amortization	(3,885)	(3,660)
Net Intangible Assets	4,988	5,174
Core deposits [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Gross Intangible Assets	4,370	4,370
Accumulated Amortization	(2,166)	(2,020)
Net Intangible Assets	2,204	2,350
Other intangible assets [Member]
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Gross Intangible Assets	4,503	4,464
Accumulated Amortization	(1,719)	(1,640)
Net Intangible Assets	$ 2,784	$ 2,824