Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Surplus	Accumulated Other Comprehensive (Loss) Income	Undivided Profits	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Undivided Profits
Balance at Dec. 31, 2019	$ 2,988,924	$ 767	$ 1,136	$ 2,117,282	$ 20,891	$ 848,848	$ (128,101)	$ (128,101)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	169,457				33,419	136,038
Stock issued for employee stock purchase plan	956		1	955
Stock-based compensation plans, net	4,406		2	4,404
Stock repurchases	(93,307)		(49)	(93,258)
Dividends on preferred stock	(26)					(26)
Dividends on common stock	(37,606)					(37,606)
Balance at Jun. 30, 2020	2,904,703	767	1,090	2,029,383	54,310	819,153
Balance at Mar. 31, 2020	2,845,400	767	1,090	2,026,420	38,230	778,893
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	74,882				16,080	58,802
Stock-based compensation plans, net	2,963			2,963
Dividends on preferred stock	(13)					(13)
Dividends on common stock	(18,529)					(18,529)
Balance at Jun. 30, 2020	2,904,703	767	1,090	2,029,383	54,310	819,153
Balance at Dec. 31, 2020	2,976,656	767	1,081	2,014,076	59,726	901,006
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	94,691				(47,653)	142,344
Stock issued for employee stock purchase plan	1,170		1	1,169
Stock-based compensation plans, net	8,965		3	8,962
Stock repurchases	(3,080)		(1)	(3,079)
Dividends on preferred stock	(26)					(26)
Dividends on common stock	(39,010)					(39,010)
Balance at Jun. 30, 2021	3,039,366	767	1,084	2,021,128	12,073	1,004,314
Balance at Mar. 31, 2021	2,930,775	767	1,083	2,017,188	(37,176)	948,913
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive (loss) income	124,173				49,249	74,924
Stock-based compensation plans, net	3,941			3,940
Dividends on preferred stock	(13)					(13)
Dividends on common stock	(19,510)					(19,510)
Balance at Jun. 30, 2021	$ 3,039,366	$ 767	$ 1,084	$ 2,021,128	$ 12,073	$ 1,004,314