CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of unrealized net gain on equity securities	$ 0				$ 280	$ (280)
Balance at beginning of period at Dec. 31, 2017	991,457	$ 938	$ 29,953	$ 503,709	481,331	(24,474)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	31,358				51,147	(19,789)
Cash dividends declared:
Series D Preferred, $35.00 per share	(26)				(26)
Common	(7,946)				(7,946)
Purchase of 1,761 shares of common stock	(97)						(97)
Issuance of shares of common stock	238,231		4,485	233,649			97
Stock based compensation	2,770			2,770
Balance at end of period at Jun. 30, 2018	1,255,747	938	34,438	740,128	524,786	(44,543)	0
Balance at beginning of period at Mar. 31, 2018	1,051,505	938	31,068	557,990	500,959	(39,450)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	22,786				27,879	(5,093)
Cash dividends declared:
Series D Preferred, $35.00 per share	(13)				(13)
Common	(4,039)				(4,039)
Issuance of shares of common stock	184,596		3,370	181,226
Stock based compensation	912			912
Balance at end of period at Jun. 30, 2018	1,255,747	938	34,438	740,128	524,786	(44,543)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of unrealized net gain on equity securities	(1,713)				(1,713)
Balance at beginning of period at Dec. 31, 2018	1,325,175	0	34,477	743,095	579,252	(31,649)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	113,454				76,666	36,788
Cash dividends declared:
Common	(11,397)				(11,397)
Issuance of shares of common stock	92,666		2,213	90,453
Stock based compensation	3,602			3,602
Balance at end of period at Jun. 30, 2019	1,521,787	0	36,690	837,150	642,808	5,139	0
Balance at beginning of period at Mar. 31, 2019	1,372,102	0	34,604	745,596	603,506	(11,604)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	61,912				45,169	16,743
Cash dividends declared:
Common	(5,867)				(5,867)
Issuance of shares of common stock	92,413		2,086	90,327
Stock based compensation	1,227			1,227
Balance at end of period at Jun. 30, 2019	$ 1,521,787	$ 0	$ 36,690	$ 837,150	$ 642,808	$ 5,139	$ 0