CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI Attributable to Parent	Preferred Stock [Member]	Accounting Standards Update 2016-13	Accounting Standards Update 2016-13 Retained Earnings
Balance (in shares) at Dec. 31, 2017		77,740,000
Balance at Dec. 31, 2017	$ 3,707,952	$ 77,740	$ 3,115,304	$ 519,144	$ (4,236)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee common stock options, stock appreciation rights, and related tax benefits (in shares)	97,877	98,000
Exercise of employee common stock options, stock appreciation rights, and related tax benefits	$ 1,851	$ 98	1,753
Repurchase of common stock (in shares)		(405,000)
Repurchase of common stock	(20,694)	$ (405)	(20,289)
Payments of Ordinary Dividends	(45,454)			45,454
Issuance of restricted common shares, net of forfeitures (in shares)		157,000
Issuance of restricted common shares, net of forfeitures	0	$ 157	(157)
Restricted shares withheld for taxes (in shares)		(106,000)
Restricted shares withheld for taxes	(6,922)	$ (106)	(6,816)
Stock-based compensation expense	17,636		17,636
Net income	359,440			359,440
Other Comprehensive Income (Loss)	(47,869)				(47,869)
Balance (in shares) at Dec. 31, 2018		77,484,000
Balance at Dec. 31, 2018	$ 3,965,940	$ 77,484	3,107,431	833,130	(52,105)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee common stock options, stock appreciation rights, and related tax benefits (in shares)	59,317	59,000
Exercise of employee common stock options, stock appreciation rights, and related tax benefits	$ 1,269	$ 59	1,210
Repurchase of common stock (in shares)		(1,102,000)
Repurchase of common stock	(61,416)	$ (1,102)	(60,314)
Payments of Ordinary Dividends	(49,828)			49,828
Issuance of restricted common shares, net of forfeitures (in shares)		211,000
Issuance of restricted common shares, net of forfeitures	0	$ 211	(211)
Restricted shares withheld for taxes (in shares)		(88,000)
Restricted shares withheld for taxes	(4,963)	$ (88)	(4,875)
Stock-based compensation expense	21,226		21,226
Net income	400,881			400,881
Other Comprehensive Income (Loss)	82,639				82,639
Balance (in shares) at Dec. 31, 2019		76,564,000
Balance at Dec. 31, 2019	4,355,748	$ 76,564	3,064,467	1,184,183	30,534
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock, net of issuance costs	$ 217,126					$ 217,126
Exercise of employee common stock options, stock appreciation rights, and related tax benefits (in shares)	17,505	18,000
Exercise of employee common stock options, stock appreciation rights, and related tax benefits	$ 410	$ 18	392
Repurchase of common stock (in shares)		(1,015,000)
Repurchase of common stock	(50,790)	$ (1,015)	(49,775)
Payments of Dividends	7,596			7,596
Payments of Ordinary Dividends	(49,389)			49,389
Issuance of restricted common shares, net of forfeitures (in shares)		255,000
Issuance of restricted common shares, net of forfeitures	0	$ 255	(255)
Issuance of common stock pursuant to restricted stock unit agreement, net of shares withheld for taxes (in shares)		86,000
Issuance of common stock pursuant to restricted stock unit agreement, net of shares withheld for taxes	2,488	$ 86	(2,574)
Restricted shares withheld for taxes (in shares)		(58,000)
Restricted shares withheld for taxes	(2,987)	$ (58)	(2,929)
Stock-based compensation expense	18,737		18,737
Net income	312,321			312,321
Cumulative effect of change in accounting principle							$ (31,796)	$ (31,796)
Other Comprehensive Income (Loss)	145,315				145,315
Balance (in shares) at Dec. 31, 2020		75,850,000
Balance at Dec. 31, 2020	$ 4,904,611	$ 75,850	$ 3,028,063	$ 1,407,723	$ 175,849	$ 217,126