Acquisition - Supplemental Pro Forma Financial Information (Details) (Valley Green Bank [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Valley Green Bank [Member]
Business Acquisition [Line Items]
Net interest income	$ 23,304	$ 22,906
Noninterest income	13,431	12,297
Noninterest expense	27,411	23,397
Net income	6,116	7,414
Earnings per share
Basic (in dollars per share)	$ 0.31	$ 0.37
Diluted (in dollars per share)	$ 0.31	$ 0.37
Integration and acquisition-related costs, net of tax	$ 1,200
Integration and acquisition-related costs, earnings per share, diluted	$ 0.06