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	$ 21,724	$ 939,674	$ 1,087,617	$ (40,415)
Balance at beginning of period at Dec. 31, 2018		36,104	21,724	939,674	1,087,617	(40,415)
Common stock withheld for taxes			(17)	(1,888)
Restricted stock grants			26	(26)
Stock-based compensation				2,009
Net income	$ 84,601				84,601
Dividends on common stock					(13,072)
Dividends on preferred stock					(1,338)
Other comprehensive income, net of tax	37,977					37,977
Balance at end of period at Jun. 30, 2019	2,152,976	36,104	21,733	939,769	1,157,808	(2,438)
Total stockholders' equity	2,152,976	36,104	21,733	939,769	1,157,808	(2,438)
Total stockholders' equity		36,104	21,733	938,801	1,123,724	(19,905)
Balance at beginning of period at Mar. 31, 2019		36,104	21,733	938,801	1,123,724	(19,905)
Common stock withheld for taxes			0	(23)
Restricted stock grants			0	0
Stock-based compensation				991
Net income	41,287				41,287
Dividends on common stock					(6,534)
Dividends on preferred stock					(669)
Other comprehensive income, net of tax	17,467					17,467
Balance at end of period at Jun. 30, 2019	2,152,976	36,104	21,733	939,769	1,157,808	(2,438)
Total stockholders' equity	2,152,976	36,104	21,733	939,769	1,157,808	(2,438)
Total stockholders' equity	2,152,976	36,104	21,733	939,769	1,157,808	(2,438)
Total stockholders' equity	2,228,073	36,104	21,736	941,652	1,221,817	6,764
Balance at beginning of period at Dec. 31, 2019	2,228,073	36,104	21,736	941,652	1,221,817	6,764
Common stock withheld for taxes			(5)	(193)
Restricted stock grants			85	(85)
Stock-based compensation				2,442
Net income	23,522				23,522
Dividends on common stock					(21,851)
Dividends on preferred stock					(1,338)
Other comprehensive income, net of tax	46,506					46,506
Balance at end of period at Jun. 30, 2020	2,214,834	36,104	21,816	943,816	1,159,828	53,270
Total stockholders' equity	2,214,834	36,104	21,816	943,816	1,159,828	53,270
Total stockholders' equity		36,104	21,816	942,516	1,150,199	49,116
Balance at beginning of period at Mar. 31, 2020		36,104	21,816	942,516	1,150,199	49,116
Common stock withheld for taxes			0	0
Restricted stock grants			0	0
Stock-based compensation				1,300
Net income	21,256				21,256
Dividends on common stock					(10,958)
Dividends on preferred stock					(669)
Other comprehensive income, net of tax	4,154					4,154
Balance at end of period at Jun. 30, 2020	2,214,834	36,104	21,816	943,816	1,159,828	53,270
Total stockholders' equity	2,214,834	36,104	21,816	943,816	1,159,828	53,270
Total stockholders' equity	$ 2,214,834	$ 36,104	$ 21,816	$ 943,816	$ 1,159,828	$ 53,270