Condensed Financial Information (Parent Company Only) - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 614,092	$ 682,122
Loans	16,845,670	16,142,124
Other assets	592,045	622,520
Total assets	27,345,674	27,461,061
LIABILITIES
Long-term debt	388,507
Total liabilities	23,919,186	24,191,699
Stockholders’ equity:
Common stock	1,252	1,270
Surplus	2,499,930	2,530,066
Undivided profits	1,329,681	1,255,586
Accumulated other comprehensive loss:
Total stockholders’ equity	3,426,488	3,269,362	$ 3,248,841	$ 2,976,656
Total liabilities and stockholders’ equity	27,345,674	27,461,061
Parent Company
ASSETS
Cash and cash equivalents	164,439	116,915
Investments in wholly-owned subsidiaries	3,603,066	3,453,961
Loans	102	1,412
Intangible assets, net	133	133
Premises and equipment	20,498	22,083
Other assets	50,642	86,622
Total assets	3,838,880	3,681,126
LIABILITIES
Long-term debt	385,285	386,798
Other liabilities	27,107	24,966
Total liabilities	412,392	411,764
Stockholders’ equity:
Common stock	1,252	1,270
Surplus	2,499,930	2,530,066
Undivided profits	1,329,681	1,255,586
Accumulated other comprehensive loss:
Unrealized depreciation on available-for-sale securities, net of income taxes of $(143,076) and $(183,124) at December 31, 2023 and 2022, respectively	(404,375)	(517,560)
Total stockholders’ equity	3,426,488	3,269,362
Total liabilities and stockholders’ equity	$ 3,838,880	$ 3,681,126