Condensed Financial Information - Parent Company - Condensed Balance Sheets (Details) - USD ($) $ in Thousands		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
ASSETS
Interest-bearing deposits in subsidiary bank		$ 503,417	$ 255,237
Total cash and cash equivalents		763,413	536,591
Securities available-for-sale, at fair value		4,617,759	4,732,762
Other assets		309,330	295,521
Total assets		13,979,418	13,105,594
LIABILITIES AND SHAREHOLDERS’ EQUITY
Total liabilities		12,372,858	11,606,694
Shareholders' equity:
Common stock		1,429	1,427
Capital surplus		689,338	681,246
Retained earnings		1,340,082	1,219,525
Accumulated other comprehensive earnings		(424,289)	(403,298)
Total shareholders’ equity		1,606,560	1,498,900	$ 1,265,737	$ 1,759,224
Total liabilities and shareholders’ equity		13,979,418	13,105,594
Subsidiary Bank [Member]
ASSETS
Cash in banks	[1]	58,957	92,905
Interest-bearing deposits in subsidiary bank	[1]	35,629	50,412
Unaffiliated Banks [Member]
ASSETS
Cash in banks	[1]	0	2
Parent Company [Member]
ASSETS
Total cash and cash equivalents		94,586	143,319	$ 119,259	$ 152,363
Securities available-for-sale, at fair value		2,124	2,200
Investment in and advances to subsidiaries, at equity	[1]	1,535,310	1,376,986
Intangible assets		723	723
Other assets		9,085	7,044
Total assets		1,641,828	1,530,272
LIABILITIES AND SHAREHOLDERS’ EQUITY
Total liabilities		35,268	31,372
Shareholders' equity:
Common stock		1,429	1,427
Capital surplus		689,338	681,246
Retained earnings		1,340,082	1,219,525
Treasury stock		(12,905)	(11,855)
Deferred compensation		12,905	11,855
Accumulated other comprehensive earnings		(424,289)	(403,298)
Total shareholders’ equity		1,606,560	1,498,900
Total liabilities and shareholders’ equity		$ 1,641,828	$ 1,530,272

[1] Eliminates in consolidation.