Consolidated Statements of Changes in Equity (Unaudited) - 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, 2014	$ 496,317			$ 81,698			$ 18,511	$ 95,816	$ 298,764			$ 1,528	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	32,400								30,869			1,531
Cash dividends declared:
Series C/D Preferred		$ (408)								$ (408)
Common, $0.20 per share	(4,119)								(4,119)
Purchase of shares of common stock	(2,173)												(2,173)
Issuance of shares of common stock	55,281						2,105	51,065					2,111
Stock based compensation	1,908							1,908
Balance at end of period at Jun. 30, 2015	579,206			81,698			20,616	148,789	325,106			3,059	(62)
Balance at beginning 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	47,519								40,979			6,540
Cash dividends declared:
Series C/D Preferred		(168)	$ (52)							$ (168)	$ (52)
Common, $0.20 per share	(4,910)								(4,910)
Redemption of Series C preferred stock		$ (81,698)			$ (81,698)
Issuance of Series D preferred stock			$ 3,777			$ 3,777
Purchase of shares of common stock	(1,698)												(1,698)
Issuance of shares of common stock	59,634						2,108	55,860					1,666
Stock based compensation	2,386							2,386
Balance at end of period at Jun. 30, 2016	$ 687,963			$ 3,777			$ 24,544	$ 274,682	$ 384,479			$ 513	$ (32)