Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Common Stock	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2020	$ 177,434	$ 3,765,406	$ 657,451	$ 47,589	$ 4,647,880
Balance (in shares) at Dec. 31, 2020	70,973,477
Increase (Decrease) in Stockholders' Equity
Net income			245,909		245,909
Other comprehensive Income (loss), net of tax effects				(23,453)	(23,453)
Total comprehensive income (loss)					222,456
Cash dividends declared on common stock per share			(66,685)		(66,685)
Cash dividends equivalents paid on restricted stock units			(91)		(91)
Employee stock purchases	$ 18	466			484
Employee stock purchases (in shares)	7,097
Stock options exercised	$ 106	1,801			1,907
Stock options exercised (in shares)	42,697
Stock issued pursuant to restricted stock units	$ 180	(180)
Stock issued pursuant to restricted stock units (in shares)	71,770
Common stock repurchased - buyback plan	$ (1,750)	(58,411)			(60,161)
Common stock repurchased - buyback plan (in shares)	(700,000)
Common stock repurchased	$ (31)	(935)			(966)
Common stock repurchased (in shares)	(12,313)
Share-based compensation expense		12,799			12,799
Balance at Jun. 30, 2021	$ 175,957	3,720,946	836,584	24,136	4,757,623
Balance (in shares) at Jun. 30, 2021	70,382,728
Balance at Mar. 31, 2021	$ 177,651	3,772,248	770,952	(1,031)	4,719,820
Balance (in shares) at Mar. 31, 2021	71,060,446
Increase (Decrease) in Stockholders' Equity
Net income			98,960		98,960
Other comprehensive Income (loss), net of tax effects				25,167	25,167
Total comprehensive income (loss)					124,127
Cash dividends declared on common stock per share			(33,305)		(33,305)
Cash dividends equivalents paid on restricted stock units			(23)		(23)
Employee stock purchases	$ 18	466			484
Employee stock purchases (in shares)	7,097
Stock options exercised	$ 12	124			136
Stock options exercised (in shares)	4,843
Stock issued pursuant to restricted stock units	$ 31	(31)
Stock issued pursuant to restricted stock units (in shares)	12,308
Common stock repurchased - buyback plan	$ (1,750)	(58,411)			(60,161)
Common stock repurchased - buyback plan (in shares)	(700,000)
Common stock repurchased	$ (5)	(157)			(162)
Common stock repurchased (in shares)	(1,966)
Share-based compensation expense		6,707			6,707
Balance at Jun. 30, 2021	$ 175,957	3,720,946	836,584	24,136	4,757,623
Balance (in shares) at Jun. 30, 2021	70,382,728
Balance at Dec. 31, 2021	$ 173,331	3,653,098	997,657	(21,146)	$ 4,802,940
Balance (in shares) at Dec. 31, 2021	69,332,297				69,332,297
Increase (Decrease) in Stockholders' Equity
Net income			219,504		$ 219,504
Other comprehensive Income (loss), net of tax effects				(469,738)	(469,738)
Total comprehensive income (loss)					(250,234)
Cash dividends declared on common stock per share			(70,805)		(70,805)
Cash dividends equivalents paid on restricted stock units			(126)		(126)
Employee stock purchases	$ 23	681			704
Employee stock purchases (in shares)	9,078
Stock options exercised	$ 45	692			737
Stock options exercised (in shares)	18,256
Restricted stock awards	$ (3)	3
Restricted stock awards (in shares)	(1,266)
Stock issued pursuant to restricted stock units	$ 912	(911)			1
Stock issued pursuant to restricted stock units (in shares)	364,809
Common stock repurchased - buyback plan	$ (3,280)	(106,924)			(110,204)
Common stock repurchased - buyback plan (in shares)	(1,312,038)
Common stock repurchased	$ (252)	(7,927)			(8,179)
Common stock repurchased (in shares)	(100,617)
Share-based compensation expense		17,799			17,799
Common stock issued for acquisition	$ 18,327	641,445			659,772
Common stock issued for acquisition (in shares)	7,330,803
Net fair value of unvested equity awards assumed in the Atlantic Capital acquisition		(1,980)			(1,980)
Balance at Jun. 30, 2022	$ 189,103	4,195,976	1,146,230	(490,884)	$ 5,040,425
Balance (in shares) at Jun. 30, 2022	75,641,322				75,641,322
Balance at Mar. 31, 2022	$ 189,403	4,214,897	1,064,064	(293,956)	$ 5,174,408
Balance (in shares) at Mar. 31, 2022	75,761,018
Increase (Decrease) in Stockholders' Equity
Net income			119,175		119,175
Other comprehensive Income (loss), net of tax effects				(196,928)	(196,928)
Total comprehensive income (loss)					(77,753)
Cash dividends declared on common stock per share			(36,983)		(36,983)
Cash dividends equivalents paid on restricted stock units			(26)		(26)
Employee stock purchases	$ 23	681			704
Employee stock purchases (in shares)	9,078
Stock options exercised	$ 21	308			329
Stock options exercised (in shares)	8,553
Restricted stock awards	$ (3)	3
Restricted stock awards (in shares)	(1,266)
Stock issued pursuant to restricted stock units	$ 591	(590)			1
Stock issued pursuant to restricted stock units (in shares)	236,507
Common stock repurchased - buyback plan	$ (750)	(22,996)			(23,746)
Common stock repurchased - buyback plan (in shares)	(300,000)
Common stock repurchased	$ (182)	(5,640)			(5,822)
Common stock repurchased (in shares)	(72,568)
Share-based compensation expense		9,313			9,313
Balance at Jun. 30, 2022	$ 189,103	$ 4,195,976	$ 1,146,230	$ (490,884)	$ 5,040,425
Balance (in shares) at Jun. 30, 2022	75,641,322				75,641,322