Parent Company Condensed Financial Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets [Abstract]
Securities available for sale	$ 152,817				$ 144,646				$ 152,817	$ 144,646
Other assets	32,111				30,671				32,111	30,671
Total assets	977,018				928,124				977,018	928,124	904,137
Liabilities and shareholders' equity [Abstract]
Trust preferred capital notes	20,620				20,620				20,620	20,620
Other liabilities	25,054				23,356				25,054	23,356
Shareholders' equity	102,197				96,090				102,197	96,090	92,777	88,876
Total liabilities and shareholders' equity	977,018				928,124				977,018	928,124
Income Statement [Abstract]
Interest expense on borrowings									(3,799)	(3,892)	(3,998)
Other income	8,820	9,570	7,729	7,383	7,091	7,140	6,358	6,457	2,266	1,132	1,808
Other expenses	(16,651)	(16,987)	(15,227)	(15,057)	(14,243)	(13,923)	(13,969)	(13,949)	(16,434)	(15,276)	(19,638)
Net income	3,888	4,533	4,181	3,780	3,411	3,513	3,083	2,969	16,382	12,976	8,110
Operating activities [Abstract]
Net income	3,888	4,533	4,181	3,780	3,411	3,513	3,083	2,969	16,382	12,976	8,110
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Share-based compensation									537	395	367
Net gain on securities									(11)	(13)	(70)
Increase (Decrease) in other assets									(1,280)	6	(1,238)
Increase (decrease) in other liabilities									457	396	(3,194)
Net cash provided by (used in) operating activities									29,689	27,992	(13,408)
Investing activities [Abstract]
Proceeds from maturities and calls of securities									34,100	31,098	28,693
Net cash used in investing activities									(44,766)	(31,175)	(23,106)
Financing activities [Abstract]
Net proceeds from issuance of common stock									200	41	0
Redemption of preferred stock									(10,000)	(10,000)	0
Cash dividends									(3,682)	(4,018)	(4,088)
Proceeds from exercise of stock options									1,309	694	409
Net cash provided by financing activities									29,190	5,010	8,133
Net increase (decrease) in cash and cash equivalents									14,113	1,827	(28,381)
Parent Company [Member]
Assets [Abstract]
Cash	852				586				852	586	328
Securities available for sale	103				68				103	68
Other assets	2,906				2,672				2,906	2,672
Investments in subsidiary	119,565				114,011				119,565	114,011
Total assets	123,426				117,337				123,426	117,337
Liabilities and shareholders' equity [Abstract]
Trust preferred capital notes	20,620				20,620				20,620	20,620
Other liabilities	609				627				609	627
Shareholders' equity	102,197				96,090				102,197	96,090
Total liabilities and shareholders' equity	123,426				117,337				123,426	117,337
Income Statement [Abstract]
Interest income on securities									0	0	22
Interest expense on borrowings									(987)	(986)	(999)
Dividends received from bank subsidiary									13,232	14,136	2,551
Equity in undistributed net income (loss) of subsidiary									4,246	(137)	6,573
Other income									737	647	684
Other expenses									(846)	(684)	(721)
Net income									16,382	12,976	8,110
Operating activities [Abstract]
Net income									16,382	12,976	8,110
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Equity in distributed (undistributed) earnings of subsidiary									(4,246)	137	(6,573)
Share-based compensation									537	395	367
Net gain on securities									0	0	(12)
Increase (Decrease) in other assets									(217)	12	322
Increase (decrease) in other liabilities									(17)	21	21
Net cash provided by (used in) operating activities									12,439	13,541	2,235
Investing activities [Abstract]
Proceeds from maturities and calls of securities									0	0	1,262
Investment in bank subsidiary									0	0	0
Net cash used in investing activities									0	0	1,262
Financing activities [Abstract]
Net proceeds from issuance of preferred stock									0	0	0
Net proceeds from issuance of common stock									200	41	0
Redemption of preferred stock									(10,000)	(10,000)	0
Cash dividends									(3,682)	(4,018)	(4,088)
Proceeds from exercise of stock options									1,309	694	409
Net cash provided by financing activities									(12,173)	(13,283)	(3,679)
Net increase (decrease) in cash and cash equivalents									266	258	(182)
Cash at beginning of year				586				328	586	328	510
Cash at end of year	$ 852				$ 586				$ 852	$ 586	$ 328