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			368,697		368,697
Other comprehensive loss, net of tax effects				(48,109)	(48,109)
Total comprehensive income (loss)					320,588
Cash dividends declared on common stock per share			(100,990)		(100,990)
Cash dividends equivalents paid on restricted stock units			(114)		(114)
Employee stock purchases	$ 40	1,111			1,151
Employee stock purchases (in shares)	15,920
Stock options exercised	$ 129	2,251			2,380
Stock options exercised (in shares)	51,620
Stock issued pursuant to restricted stock units	$ 187	(187)
Stock issued pursuant to restricted stock units (in shares)	74,878
Common stock repurchased - buyback plan	$ (2,964)	(93,216)			(96,180)
Common stock repurchased - buyback plan (in shares)	(1,185,491)
Common stock repurchased	$ (31)	(938)			(969)
Common stock repurchased (in shares)	(12,367)
Share-based compensation expense		19,195			19,195
Balance at Sep. 30, 2021	$ 174,795	3,693,622	925,044	(520)	4,792,941
Balance (in shares) at Sep. 30, 2021	69,918,037
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
Increase (Decrease) in Stockholders' Equity
Net income			122,788		122,788
Other comprehensive loss, net of tax effects				(24,656)	(24,656)
Total comprehensive income (loss)					98,132
Cash dividends declared on common stock per share			(34,305)		(34,305)
Cash dividends equivalents paid on restricted stock units			(23)		(23)
Employee stock purchases	$ 22	645			667
Employee stock purchases (in shares)	8,823
Stock options exercised	$ 22	451			473
Stock options exercised (in shares)	8,923
Stock issued pursuant to restricted stock units	$ 8	(8)
Stock issued pursuant to restricted stock units (in shares)	3,108
Common stock repurchased - buyback plan	$ (1,214)	(34,805)			(36,019)
Common stock repurchased - buyback plan (in shares)	(485,491)
Common stock repurchased		(3)			(3)
Common stock repurchased (in shares)	(54)
Share-based compensation expense		6,396			6,396
Balance at Sep. 30, 2021	$ 174,795	3,693,622	925,044	(520)	4,792,941
Balance (in shares) at Sep. 30, 2021	69,918,037
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			352,547		$ 352,547
Other comprehensive loss, net of tax effects				(695,312)	(695,312)
Total comprehensive income (loss)					(342,765)
Cash dividends declared on common stock per share			(108,639)		(108,639)
Cash dividends equivalents paid on restricted stock units			(152)		(152)
Employee stock purchases	$ 48	1,395			1,443
Employee stock purchases (in shares)	19,162
Stock options exercised	$ 92	1,424			1,516
Stock options exercised (in shares)	37,236
Restricted stock awards (forfeitures)	$ (6)	6
Restricted stock awards (forfeitures)(in shares)	(2,816)
Stock issued pursuant to restricted stock units	$ 958	(957)			1
Stock issued pursuant to restricted stock units (in shares)	383,369
Common stock repurchased - buyback plan	$ (3,280)	(106,924)			(110,204)
Common stock repurchased - buyback plan (in shares)	(1,312,038)
Common stock repurchased	$ (279)	(8,778)			(9,057)
Common stock repurchased (in shares)	(111,568)
Share-based compensation expense		28,311			28,311
Common stock issued for Atlantic Capital merger	$ 18,327	641,445			659,772
Common stock issued for Atlantic Capital merger (in shares)	7,330,803
Net fair value of unvested equity awards assumed in the Atlantic Capital acquisition		(1,980)			(1,980)
Balance at Sep. 30, 2022	$ 189,191	4,207,040	1,241,413	(716,458)	$ 4,921,186
Balance (in shares) at Sep. 30, 2022	75,676,445				75,676,445
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
Increase (Decrease) in Stockholders' Equity
Net income			133,043		133,043
Other comprehensive loss, net of tax effects				(225,574)	(225,574)
Total comprehensive income (loss)					(92,531)
Cash dividends declared on common stock per share			(37,834)		(37,834)
Cash dividends equivalents paid on restricted stock units			(26)		(26)
Employee stock purchases	$ 25	714			739
Employee stock purchases (in shares)	10,084
Stock options exercised	$ 47	732			779
Stock options exercised (in shares)	18,980
Restricted stock awards	$ (3)	3
Restricted stock awards (in shares)	(1,550)
Stock issued pursuant to restricted stock units	$ 46	(46)
Stock issued pursuant to restricted stock units (in shares)	18,560
Common stock repurchased	$ (27)	(851)			(878)
Common stock repurchased (in shares)	(10,951)
Share-based compensation expense		10,512			10,512
Balance at Sep. 30, 2022	$ 189,191	$ 4,207,040	$ 1,241,413	$ (716,458)	$ 4,921,186
Balance (in shares) at Sep. 30, 2022	75,676,445				75,676,445