Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Series C Preferred Stock	Series D Preferred Stock	Preferred Stock	Preferred Stock Series C Preferred Stock	Preferred Stock Series D Preferred Stock	Common Stock	Capital Surplus	Retained Earnings	Retained Earnings Series C Preferred Stock	Retained Earnings Series D Preferred Stock	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance at beginning of period at Dec. 31, 2013	$ 439,460			$ 81,698			$ 18,399	$ 91,632	$ 265,067			$ (17,336)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	60,764								41,900			18,864
Cash dividends declared:
Preferred	(817)								(817)
Common	(7,386)								(7,386)
Purchase of shares of treasury stock	(899)												(899)
Issuance of shares of common stock	1,797						112	786					899
Stock based compensation	3,398							3,398
Balance at end of period at Dec. 31, 2014	496,317			81,698			18,511	95,816	298,764			1,528	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	52,487								60,042			(7,555)
Cash dividends declared:
Preferred	(817)								(817)
Common	(9,359)								(9,359)
Purchase of shares of treasury stock	(2,987)												(2,987)
Issuance of shares of common stock	124,254						3,925	117,342					2,987
Stock based compensation	3,278							3,278
Balance at end of period at Dec. 31, 2015	663,173			81,698			22,436	216,436	348,630			(6,027)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	55,330								80,349			(25,019)
Cash dividends declared:
Preferred	(124)	$ (168)								$ (168)	$ (124)
Common	(12,578)								(12,578)
Purchase of shares of treasury stock	(3,719)												(3,719)
Issuance of shares of common stock	115,865						3,684	108,462					3,719
Stock based compensation	3,478							3,478
Redemption of preferred stock		$ (81,698)	$ (2,420)		$ (81,698)	$ (2,420)
Issuance of Series D preferred stock			$ 3,777			$ 3,777
Balance at end of period at Dec. 31, 2016	$ 740,916			$ 1,357			$ 26,120	$ 328,376	$ 416,109			$ (31,046)	$ 0