Earnings Per Share (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic Net Income per Common Share Available to Common Stockholders [Abstract]
Net income	$ 3,619,000	$ 3,910,000	$ 3,665,000	$ 3,528,000	$ 3,509,000	$ 3,647,000	$ 3,479,000	$ 3,390,000	$ 14,722,000	$ 14,025,000	$ 11,372,000
Preferred stock dividends									(4,417,000)	(4,252,000)	(3,576,000)
Net income available to common stockholders	2,515,000	2,806,000	2,560,000	2,424,000	2,405,000	2,543,000	2,374,000	2,451,000	10,305,000	9,773,000	7,796,000
Weighted average common shares outstanding									5,934,628	6,023,289	6,042,015
Basic earnings per common share	$ 0.43	$ 0.47	$ 0.43	$ 0.41	$ 0.40	$ 0.42	$ 0.39	$ 0.41	$ 1.74	$ 1.62	$ 1.29
Diluted Net Income per Common Share Available to Common Stockholders [Abstract]
Net income available to common stockholders	2,515,000	2,806,000	2,560,000	2,424,000	2,405,000	2,543,000	2,374,000	2,451,000	10,305,000	9,773,000	7,796,000
Effect of assumed preferred stock conversion									0	0	0
Net income applicable to diluted earnings per share									$ 10,305,000	$ 9,773,000	$ 7,796,000
Weighted average common shares outstanding									5,934,628	6,023,289	6,042,015
Dilutive potential common shares [Abstract]
Assumed conversion of stock options									2,090	4,473	10,515
Restricted stock awarded									8,184	116	1,741
Assumed conversion of preferred stock									0	0	0
Dilutive potential common shares									10,274	4,589	12,256
Diluted weighted average common shares outstanding									5,944,902	6,027,878	6,054,271
Diluted earnings per common share	$ 0.42	$ 0.47	$ 0.43	$ 0.41	$ 0.40	$ 0.42	$ 0.39	$ 0.41	$ 1.73	$ 1.62	$ 1.29
Stock options to purchase shares of common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share (in shares)									130,500	108,125	202,970
Average dilutive potential common shares associated with convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share (in shares)									2,494,801	2,290,110	1,998,652