Consolidated Statements of Stockholders' Equity (Unaudited) (USD $)	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Income	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2011	$ 63,830,000			$ 29,636,000	$ 33,986,000	$ 208,000
Beginning Balance, shares at Dec. 31, 2011		1,247,700	6,202,485
Net income	6,968,000				6,968,000
Change in unrealized gain on available-for-sale securities, net of income taxes	770,000					770,000
Exercise of common stock options, shares			145,594
Exercise of common stock warrants, shares			31,921
Exercise of common stock warrants, value	195,000			195,000
Excess tax benefit from stock options exercised	437,000			437,000
Conversion of preferred stock to common stock, Share		(201,141)	201,141
Common stock dividends	(2,274,000)				(2,274,000)
Preferred stock dividends	(181,000)				(181,000)
Stock-based compensation	53,000			53,000
Ending Balance at Mar. 31, 2012	69,798,000			30,321,000	38,499,000	978,000
Ending Balance, shares at Mar. 31, 2012		1,046,559	6,581,141
Beginning Balance at Dec. 31, 2012	121,253,000			63,875,000	55,758,000	1,620,000
Beginning Balance, shares at Dec. 31, 2012		241,182	10,877,537
Net income	20,387,000				20,387,000
Change in unrealized gain on available-for-sale securities, net of income taxes	165,000					165,000
Conversion of preferred stock to common stock, Share		(30,627)	30,627
Forfeiture of restricted stock, Share			(920)
Common stock dividends	(2,454,000)				(2,454,000)
Preferred stock dividends	(34,000)				(34,000)
Tax benefit from restricted stock dividends	22,000			22,000
Stock-based compensation	389,000			389,000
Ending Balance at Mar. 31, 2013	$ 139,728,000			$ 64,286,000	$ 73,657,000	$ 1,785,000
Ending Balance, shares at Mar. 31, 2013		210,555	10,907,244