Parent Holding Company Information (Condensed) - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities
Net income	$ 54,316	$ 52,445	$ 54,955	$ 61,211	$ 79,677	$ 79,338	$ 76,392	$ 67,795	$ 222,927	$ 303,202	$ 284,757
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation, net of tax benefits									5,929	5,366	4,349
Net cash provided by operating activities									500,715	470,660	572,049
Investing Activities
Net additions of premises and equipment									(49,283)	(23,238)	(9,436)
Net cash used in investing activities									(207,492)	(1,351,782)	(3,906,701)
Financing Activities
Net decrease in other borrowed funds									3,327	9,120	3,526
Cash dividends paid									(146,690)	(157,540)	(145,557)
Tax withholding payments for stock-based compensation									(1,795)	(1,704)	(1,553)
Proceeds from stock option exercises									0	140	265
Net cash provided by financing activities									659,124	845,431	3,139,196
Net increase (decrease) in cash, cash equivalents and restricted cash									952,347	(35,691)	(195,456)
Cash, cash equivalents and restricted cash at beginning of period				401,995				437,686	401,995	437,686	633,142
Cash, cash equivalents and restricted cash at end of period	1,354,342				401,995				1,354,342	401,995	437,686
Parent Company
Operating Activities
Net income									222,927	303,202	284,757
Adjustments to reconcile net income to net cash provided by operating activities:
Subsidiary income in excess of dividends distributed									(58,835)	(191,258)	(91,336)
Stock-based compensation, net of tax benefits									1,742	1,685	1,628
Net change in other assets and other liabilities									7,788	1,794	(7,245)
Net cash provided by operating activities									173,622	115,423	187,804
Investing Activities
Net additions of premises and equipment									(3)	(4)	(13)
Proceeds from sale of marketable equity securities									0	63	186
Equity received from subsidiaries									0	0	248
Net cash used in investing activities									(3)	59	421
Financing Activities
Net decrease in other borrowed funds									0	0	(7,500)
Cash dividends paid									(146,690)	(157,540)	(145,557)
Tax withholding payments for stock-based compensation									(1,795)	(1,704)	(1,553)
Proceeds from stock option exercises									0	140	265
Net cash provided by financing activities									(148,485)	(159,104)	(154,345)
Net increase (decrease) in cash, cash equivalents and restricted cash									25,134	(43,622)	33,880
Cash, cash equivalents and restricted cash at beginning of period				$ 75,684				$ 119,306	75,684	119,306	85,426
Cash, cash equivalents and restricted cash at end of period	$ 100,818				$ 75,684				$ 100,818	$ 75,684	$ 119,306