Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
ASSETS
Cash and cash equivalents	$ 687,377	$ 614,092
Loans	17,005,937	16,845,670
Other assets	572,385	592,045
Total assets	26,876,049	27,345,674	$ 27,461,061
LIABILITIES
Long-term debt	386,665
Total liabilities	23,347,177	23,919,186
Stockholders’ equity:
Common stock	1,257	1,252
Surplus	2,511,590	2,499,930
Undivided profits	1,376,935	1,329,681
Accumulated other comprehensive loss:
Total stockholders’ equity	3,528,872	3,426,488	$ 3,269,362	$ 3,248,841
Total liabilities and stockholders’ equity	26,876,049	27,345,674
Parent Company
ASSETS
Cash and cash equivalents	287,066	164,439
Investments in wholly-owned subsidiaries	3,570,446	3,603,066
Loans	0	102
Intangible assets, net	133	133
Premises and equipment	18,929	20,498
Other assets	75,707	50,642
Total assets	3,952,281	3,838,880
LIABILITIES
Long-term debt	383,720	385,285
Other liabilities	39,689	27,107
Total liabilities	423,409	412,392
Stockholders’ equity:
Common stock	1,257	1,252
Surplus	2,511,590	2,499,930
Undivided profits	1,376,935	1,329,681
Accumulated other comprehensive loss:
Unrealized depreciation on available-for-sale securities, net of income taxes of $(127,698) and $(143,076) at December 31, 2024 and 2023, respectively	(360,910)	(404,375)
Total stockholders’ equity	3,528,872	3,426,488
Total liabilities and stockholders’ equity	$ 3,952,281	$ 3,838,880