CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock Outstanding [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), net of tax [Member]
Stockholders Equity		$ 36,104	$ 21,628	$ 936,772	$ 895,208	$ (20,615)
Balance at beginning of year at Dec. 31, 2017		36,104	21,628	936,772	895,208	(20,615)
Common stock issued as compensation			27	(27)
Common stock issued for exercised warrants			73	(73)
Common stock withheld for taxes			(43)	(2,784)
Restricted stock grants			40	(40)
Unrestricted stock grants			0	0
Restricted stock forfeited			(1)	1
Stock-based compensation				5,825
Net income	$ 201,608				201,608
Dividends on common stock					(6,517)
Dividends on preferred stock					(2,676)
Amounts reclassified from accumulated comprehensive loss per ASU 2016-01 | ASU 2016-01					(6)	6
OCI, net of tax	(19,806)					(19,806)
Balance at end of year at Dec. 31, 2018	2,044,704	36,104	21,724	939,674	1,087,617	(40,415)
Stockholders Equity	2,044,704	36,104	21,628	939,674	895,208	(20,615)
Stockholders Equity	2,044,704	36,104	21,724	939,674	1,087,617	(40,415)
Common stock issued as compensation			0	0
Common stock issued for exercised warrants			0	0
Common stock withheld for taxes			(18)	(1,941)
Restricted stock grants			31	(31)
Unrestricted stock grants			0	0
Restricted stock forfeited			(1)	1
Stock-based compensation				3,949
Net income	167,377				167,377
Dividends on common stock					(30,501)
Dividends on preferred stock					(2,676)
Amounts reclassified from accumulated comprehensive loss per ASU 2016-01 | ASU 2016-01					0	0
OCI, net of tax	47,179					47,179
Balance at end of year at Dec. 31, 2019	2,228,073	36,104	21,736	941,652	1,221,817	6,764
Stockholders Equity	2,044,704	36,104	21,724	939,674	1,221,817	(40,415)
Stockholders Equity	2,228,073	36,104	21,736	941,652	1,221,817	6,764
Common stock issued as compensation			0	0
Common stock issued for exercised warrants			0	0
Common stock withheld for taxes			(5)	(201)
Restricted stock grants			90	(90)
Unrestricted stock grants			2	(2)
Restricted stock forfeited			0	0
Stock-based compensation				5,117
Net income	102,273				102,273
Dividends on common stock					(43,771)
Dividends on preferred stock					(2,676)
Amounts reclassified from accumulated comprehensive loss per ASU 2016-01 | ASU 2016-01					0	0
OCI, net of tax	48,691					48,691
Balance at end of year at Dec. 31, 2020	2,275,179	36,104	21,823	946,476	1,215,321	55,455
Stockholders Equity	2,228,073	36,104	21,823	946,476	1,221,817	55,455
Stockholders Equity	$ 2,275,179	$ 36,104	$ 21,823	$ 946,476	$ 1,215,321	$ 55,455