Parent Company Statements (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Income Statements, Captions [Line Items]
Interest expense	$ (1,613)	$ (1,623)	$ (1,645)	$ (1,678)	$ (1,727)	$ (1,680)	$ (1,814)	$ (1,949)	$ (6,559)	$ (7,170)	$ (11,937)
Noninterest expense	(16,969)	(16,771)	(16,357)	(16,661)	(15,926)	(16,045)	(15,674)	(17,199)	(66,758)	(65,052)	(65,780)
Income before income taxes and equity in earnings of subsidiaries	8,312	9,842	7,943	7,358	7,080	7,924	8,644	7,865	33,455	31,513	26,676
Net income	6,355	7,069	5,689	5,179	5,088	5,479	6,109	5,559	24,292	22,235	18,664
Comprehensive income									27,861	18,506	18,941
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Dividends from subsidiaries									22,200	4,500	37,300
Interest on investments									0	18	12
Interest expense									(587)	(601)	(971)
Other income									2	1	0
Noninterest expense									(861)	(853)	(1,013)
Income before income taxes and equity in earnings of subsidiaries									20,754	3,065	35,328
Income tax credit									(485)	(415)	(669)
Income before equity in earnings of subsidiaries									21,239	3,480	35,997
Undistributed equity in (distributions in excess of) earnings of subsidiaries									3,053	18,755	(17,333)
Net income									24,292	22,235	18,664
Comprehensive income									$ 27,861	$ 18,506	$ 18,941