Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $)	Total	Preferred stock [Member]	Common stock and additional paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss) [Member]
Balance at Dec. 31, 2009	$ 147,938,000	$ 24,606,000	$ 45,218,000	$ 78,450,000	$ (336,000)
Balance (in shares) at Dec. 31, 2009	9,744,170		9,744,170
Net income	5,844,000			5,844,000
Net unrealized gain on securities available for sale, net of taxes	857,000				857,000
Unrecognized transition obligation for postretirement benefits, net of taxes	9,000				9,000
Comprehensive income	6,710,000			5,844,000	866,000
Cash dividends declared	(4,430,000)			(4,430,000)
Equity compensation expense	19,000		19,000
Amortization of premium for preferred stock issuance		49,000	(49,000)
Proceeds from sale of common stock	208,000		208,000
Proceeds from sale of common stock (in shares)			14,048
Balance at Jun. 30, 2010	150,445,000	24,655,000	45,396,000	79,864,000	530,000
Balance (in shares) at Jun. 30, 2010	9,758,218		9,758,218
Balance at Dec. 31, 2010	149,848,000	24,705,000	45,572,000	81,701,000	(2,130,000)
Balance (in shares) at Dec. 31, 2010	9,773,025		9,773,025
Net income	6,336,000			6,336,000
Net unrealized gain on securities available for sale, net of taxes	4,255,000				4,255,000
Unrecognized transition obligation for postretirement benefits, net of taxes	10,000				10,000
Comprehensive income	10,601,000			6,336,000	4,265,000
Cash dividends declared	(4,443,000)			(4,443,000)
Equity compensation expense	11,000		11,000
Amortization of premium for preferred stock issuance		49,000	(49,000)
Proceeds from sale of common stock	193,000		193,000
Proceeds from sale of common stock (in shares)			20,681
Balance at Jun. 30, 2011	$ 156,210,000	$ 24,754,000	$ 45,727,000	$ 83,594,000	$ 2,135,000
Balance (in shares) at Jun. 30, 2011	9,793,706		9,793,706