Consolidated Statements of Shareholders' Equity Statement - USD ($) $ in Thousands	Total	Preferred Stock	Preferred Stock Including Additional Paid in Capital	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, Preferred stock, Shares outstanding at Dec. 31, 2014		4,550,000
Balance, Common stock, shares outstanding at Dec. 31, 2014				54,739,111
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues				22,607
Stock Issued During Period, Shares, Restricted Stock Award, Gross				263,829
Shares Paid for Tax Withholding for Share Based Compensation				(67,296)
Balance, Preferred stock, Shares outstanding at Dec. 31, 2015		4,550,000
Balance, Common stock, shares outstanding at Dec. 31, 2015				49,047,335
Balance at Dec. 31, 2014	$ 607,302		$ 109,658	$ 547	$ 763,935	$ 21,316	$ (288,154)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance	166			0	166
Restricted stock granted, net of amortization	2,965			3	2,962
Adjustments for tax withholding on share-based compensation	(557)			$ (1)	(556)
Stock issuance costs	(37)				(37)
Stock Repurchased During Period, Shares				(5,910,916)
Stock Repurchased During Period, Value	(41,171)			$ (59)	(41,112)
Net income	16,544						16,544
Dividends on preferred stock	(9,176)						(9,176)
Dividends on common stock	(49,927)						(49,927)
Other comprehensive income	(34,084)					(34,084)
Balance at Dec. 31, 2015	$ 492,025		109,658	$ 490	725,358	(12,768)	(330,713)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		21,937		20,582
Stock Issued During Period, Shares, Restricted Stock Award, Gross				214,878
Shares Paid for Tax Withholding for Share Based Compensation				(80,888)
Balance, Preferred stock, Shares outstanding at Dec. 31, 2016	4,571,937	4,571,937
Balance, Common stock, shares outstanding at Dec. 31, 2016	49,153,463			49,153,463
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance	$ 685		548	$ 1	136
Restricted stock granted, net of amortization	2,709			2	2,707
Adjustments for tax withholding on share-based compensation	(485)			$ (1)	(484)
Stock issuance costs	(239)		(201)		(38)
Stock Repurchased During Period, Shares				(48,444)
Stock Repurchased During Period, Value	(310)			$ 0	(310)
Net income	43,099						43,099
Dividends on preferred stock	(9,185)						(9,185)
Dividends on common stock	(41,274)						(41,274)
Other comprehensive income	(19,841)					(19,841)
Balance at Dec. 31, 2016	$ 467,184		110,005	$ 492	727,369	(32,609)	(338,073)
Preferred stock, shares issued	4,571,937
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		1,316,743		6,617,487
Stock Issued During Period, Shares, Restricted Stock Award, Gross				138,166
Shares Paid for Tax Withholding for Share Based Compensation				(77,567)
Balance, Preferred stock, Shares outstanding at Dec. 31, 2017	5,888,680	5,888,680
Balance, Common stock, shares outstanding at Dec. 31, 2017	55,831,549			55,831,549
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issuance	$ 78,532		31,350	$ 66	47,116
Restricted stock granted, net of amortization	1,954			1	1,953
Adjustments for tax withholding on share-based compensation	(521)			(1)	(520)
Stock issuance costs	(106)		(61)		(45)
Net income	33,893						33,893
Dividends on preferred stock	(10,794)						(10,794)
Dividends on common stock	(36,996)						(36,996)
Other comprehensive income	23,912					23,912
Balance at Dec. 31, 2017	$ 557,058		$ 141,294	$ 558	$ 775,873	$ (8,697)	$ (351,970)
Preferred stock, shares issued	5,888,680