CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) (USD $)	Preferred Stock [Member]	Common Stock [Member]	Warrants [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comp. Income, net [Member]	Total
Balances at Dec. 31, 2010	$ 90,788,682	$ 33,870,380	$ 3,348,402	$ 530,829,019	$ 12,996,202	$ 5,624,600	$ 677,457,285
Balances (in shares) at Dec. 31, 2010		33,870,380
Exercise of employee common stock options and related tax benefits	0	106,919	0	612,280	0	0	719,199
Exercise of employee common stock options and related tax benefits (in shares)		106,919
Issuance of restricted common shares, net of forfeitures	0	158,303	0	(158,303)	0	0	0
Issuance of restricted common shares, net of forfeitures (in shares)		158,303
Issuance of Salary Stock Units	0	18,680	0	272,501	0	0	291,181
Issuance of Salary Stock Units (in shares)		18,680
Restricted shares withheld for taxes	0	(18,119)	0	(249,341)	0	0	(267,460)
Restricted shares withheld for taxes (in shares)		(18,119)
Compensation expense for restricted shares	0	0	0	1,570,425	0	0	1,570,425
Compensation expense for stock options	0	0	0	680,761	0	0	680,761
Accretion on preferred stock discount	633,631	0	0	0	(633,631)	0	0
Preferred dividends paid	0	0	0	0	(2,375,000)	0	(2,375,000)
Net income	0	0	0	0	9,876,571	0	9,876,571
Other comprehensive income						11,275,060	11,275,060
Balances at Jun. 30, 2011	91,422,313	34,136,163	3,348,402	533,557,342	19,864,142	16,899,660	699,228,022
Balances (in shares) at Jun. 30, 2011		34,136,163
Balances at Dec. 31, 2011	69,096,828	34,354,960	3,348,402	536,227,537	49,783,584	17,333,257	710,144,568
Balances (in shares) at Dec. 31, 2011		34,354,960
Exercise of employee common stock options and related tax benefits	0	213,760	0	1,150,474	0	0	1,364,234
Exercise of employee common stock options and related tax benefits (in shares)		213,760
Repurchase of preferred stock	(71,250,000)	0	0	0	0	0	(71,250,000)
Issuance of restricted common shares, net of forfeitures	0	94,110	0	(94,110)	0	0	0
Issuance of restricted common shares, net of forfeitures (in shares)		94,110
Issuance of Salary Stock Units	0	57,508	0	942,565	0	0	1,000,073
Issuance of Salary Stock Units (in shares)		57,508
Restricted shares withheld for taxes	0	(44,425)	0	(686,321)	0	0	(730,746)
Restricted shares withheld for taxes (in shares)		(44,425)
Compensation expense for restricted shares	0	0	0	1,671,568	0	0	1,671,568
Compensation expense for stock options	0	0	0	250,653	0	0	250,653
Accretion on preferred stock discount	2,153,172	0	0	0	(2,153,172)	0	0
Preferred dividends paid	0	0	0	0	(2,127,605)	0	(2,127,605)
Net income	0	0	0	0	18,804,598	0	18,804,598
Other comprehensive income	0	0	0	0	0	159,212	159,212
Balances at Jun. 30, 2012	$ 0	$ 34,675,913	$ 3,348,402	$ 539,462,366	$ 64,307,405	$ 17,492,469	$ 659,286,555
Balances (in shares) at Jun. 30, 2012		34,675,913					34,675,913