Consolidated Statements of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Balance as of beginning of period at Dec. 31, 2008	$ 140,409	$ 41,749	$ 122	$ 366,817	$ (3,949)	$ (264,330)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance	12,799		17	12,782
Granting and vesting of restricted stock	118		0	118
Net income	17,581					17,581
Dividends on preferred stock	(4,010)					(4,010)
Dividends on common stock	(12,154)					(12,154)
Other comprehensive loss	14,010				14,010
Balance as of end of period at Dec. 31, 2009	168,753	41,749	139	379,717	10,061	(262,913)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance	117,070		122	116,948
Granting and vesting of restricted stock	60		0	60
Conversion of preferred shares to common shares	0	(41,749)	42	41,707
Capitalized expenses associated with stock issuances	(128)			(128)
Cumulative effect of adoption of new accounting principle	12					12
Net income	29,472					29,472
Dividends on preferred stock	(3,061)					(3,061)
Dividends on common stock	(19,817)					(19,817)
Other comprehensive loss	(4)				(4)
Balance as of end of period at Dec. 31, 2010	292,357	0	303	538,304	10,057	(256,307)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuance	95,424		97	95,327
Granting and vesting of restricted stock	1,198		4	1,194
Capitalized expenses associated with stock issuances	(142)			(142)
Net income	39,812					39,812
Dividends on preferred stock	0
Dividends on common stock	(43,988)					(43,988)
Other comprehensive loss	(13,312)				(13,312)
Balance as of end of period at Dec. 31, 2011	$ 371,349	$ 0	$ 404	$ 634,683	$ (3,255)	$ (260,483)