CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Total stockholders' equity		$ 36,104	$ 21,628	$ 936,772	$ 895,208	$ (20,615)
Balance at beginning of period at Dec. 31, 2017		36,104	21,628	936,772	895,208	(20,615)
Common stock issued as compensation			15	(15)
Common stock withheld for taxes			(38)	(2,586)
Restricted stock grants			34	(34)
Stock-based compensation				2,205
Net income	$ 33,148				33,148
Dividends on preferred stock	(669)				(669)
Dividends on common stock					0
Amount reclassified from accumulated other comprehensive loss per ASU 2016-1					(6)	6
Other comprehensive income (loss), net of tax	(24,053)					(24,053)
Balance at end of period at Mar. 31, 2018	1,877,104	36,104	21,639	936,342	927,681	(44,662)
Total stockholders' equity	1,877,104	36,104	21,639	936,342	895,208	(20,615)
Total stockholders' equity	1,877,104	36,104	21,639	936,342	927,681	(44,662)
Total stockholders' equity	2,044,704	36,104	21,724	939,674	1,087,617	(40,415)
Balance at beginning of period at Dec. 31, 2018	2,044,704	36,104	21,724	939,674	1,087,617	(40,415)
Common stock issued as compensation			0	0
Common stock withheld for taxes			(17)	(1,865)
Restricted stock grants			26	(26)
Stock-based compensation				1,018
Net income	43,314				43,314
Dividends on preferred stock	(669)				(669)
Dividends on common stock					(6,538)
Amount reclassified from accumulated other comprehensive loss per ASU 2016-1					0	0
Other comprehensive income (loss), net of tax	20,510					20,510
Balance at end of period at Mar. 31, 2019	2,100,457	36,104	21,733	938,801	1,123,724	(19,905)
Total stockholders' equity	2,100,457	36,104	21,733	938,801	1,087,617	(40,415)
Total stockholders' equity	$ 2,100,457	$ 36,104	$ 21,733	$ 938,801	$ 1,123,724	$ (19,905)