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]
Retained earnings adjustment for adoption of leasing standard	$ 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	59,789				84,857	(25,068)
Cash dividends declared:
Series D Preferred	(39)				(39)
Common	(12,767)				(12,767)
Conversion of Series D Preferred Stock	(938)	(938)
Purchase of shares of common stock	(97)						(97)
Issuance of shares of common stock	239,299		4,520	234,682			97
Stock based compensation	3,689			3,689
Balance at end of period at Sep. 30, 2018	1,280,393	0	34,473	742,080	553,662	(49,822)	0
Balance at beginning 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]
Comprehensive income	28,431				33,710	(5,279)
Cash dividends declared:
Series D Preferred	(13)				(13)
Common	(4,821)				(4,821)
Conversion of Series D Preferred Stock	(938)	(938)
Issuance of shares of common stock	1,068		35	1,033
Stock based compensation	919			919
Balance at end of period at Sep. 30, 2018	1,280,393	0	34,473	742,080	553,662	(49,822)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained earnings adjustment for adoption of leasing standard	(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	160,715				111,278	49,437
Cash dividends declared:
Common	(18,001)				(18,001)
Issuance of shares of common stock	92,834		2,219	90,615
Stock based compensation	4,833			4,833
Balance at end of period at Sep. 30, 2019	1,563,843	0	36,696	838,543	670,816	17,788	0
Balance at beginning of period at Jun. 30, 2019	1,521,787	0	36,690	837,150	642,808	5,139	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	47,261				34,612	12,649
Cash dividends declared:
Common	(6,604)				(6,604)
Issuance of shares of common stock	168		6	162
Stock based compensation	1,231			1,231
Balance at end of period at Sep. 30, 2019	$ 1,563,843	$ 0	$ 36,696	$ 838,543	$ 670,816	$ 17,788	$ 0