Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands		Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock Outstanding [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI Attributable to Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Treasury Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2018								80,501,948
Balance at Dec. 31, 2018								$ 898	$ 942,062	$ (18,006)	$ 1,479,149	$ (282,237)	$ 2,121,866
Dividend Reinvestment Plan (in shares)								93,143					93,143
Dividend Reinvestment Plan								$ 1	3,365	0	0	0	$ 3,366
Restricted stock units vested (in shares)								123,762
Restricted stock units vested								$ 1	0	0	0	0	1
Shares withheld related to net share settlement of RSUs								$ 0	(2,311)	0	0	0	(2,311)
Stock issued to directors (in shares)								21,160
Stock issued to directors								$ 0	749	0	0	0	749
Purchases of treasury stock (in shares)								(1,010,594)
Purchases of treasury stock								$ 0	0	0	0	(36,301)	(36,301)
Stock -based compensation								0	6,601	0	0	0	6,601
Cash dividends								0	0	0	(99,131)	0	(99,131)
Other comprehensive income								0	0	20,308	0	0	20,308
Net income								$ 0	0	0	279,135	0	279,135
Balance (in shares) at Dec. 31, 2019								79,729,419
Balance at Dec. 31, 2019								$ 900	950,466	2,302	1,659,153	(318,538)	$ 2,294,283
Dividend Reinvestment Plan (in shares)								358,157					358,157
Dividend Reinvestment Plan								$ 4	9,773	0	0	0	$ 9,777
Restricted stock units vested (in shares)								189,557
Restricted stock units vested								$ 2	0	0	0	0	2
Shares withheld related to net share settlement of RSUs								$ 0	(1,911)	0	0	0	(1,911)
Stock issued to directors (in shares)								31,110
Stock issued to directors								$ 0	800	0	0	0	800
Purchases of treasury stock (in shares)								(799,978)
Purchases of treasury stock								$ 0	0	0	0	(23,593)	(23,593)
Stock -based compensation								0	5,606	0	0	0	5,606
Cash dividends								0	0	0	(98,688)	0	(98,688)
Other comprehensive income								0	0	3,008	0	0	3,008
Net income								$ 0	0	0	228,860	0	228,860
Balance (in shares) at Dec. 31, 2020								79,508,265
Balance (Accounting Standards Update 2016-13 [Member]) at Dec. 31, 2020	[1]	$ 0	$ 0	$ 0	$ (3,139)	$ 0	$ (3,139)
Balance at Dec. 31, 2020								$ 906	964,734	5,310	1,789,325	(342,131)	$ 2,418,144
Dividend Reinvestment Plan (in shares)								84,011					84,011
Dividend Reinvestment Plan								$ 1	3,562	0	0	0	$ 3,563
Restricted stock units vested (in shares)								123,893
Restricted stock units vested								$ 2	0	0	0	0	2
Shares withheld related to net share settlement of RSUs								$ 0	(2,632)	0	0	0	(2,632)
Stock issued to directors (in shares)								20,750
Stock issued to directors								$ 0	850	0	0	0	$ 850
Purchases of treasury stock (in shares)								(3,986,057)					(3,986,057)
Purchases of treasury stock								$ 0	0	0	0	(167,104)	$ (167,104)
Stock -based compensation								0	5,960	0	0	0	5,960
Cash dividends								0	0	0	(99,322)	0	(99,322)
Other comprehensive income								0	0	(8,375)	0	0	(8,375)
Net income								$ 0	0	0	298,304	0	298,304
Balance (in shares) at Dec. 31, 2021								75,750,862
Balance at Dec. 31, 2021								$ 909	$ 972,474	$ (3,065)	$ 1,985,168	$ (509,235)	$ 2,446,251

[1] Represents the impact of the adoption of Accounting Standards Update ASU 2016-13, Financial Instruments — Credit Losses (Topic 326) on January 1, 2021.