Loans and Allowances for Credit Losses, Activity in Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 278,594	$ 281,623	$ 280,035	$ 277,123	$ 277,123
Provision for loan losses	(984)	13,148	(1,320)	23,108
Loans charged off	(1,313)	(7,940)	(3,604)	(15,000)
Recoveries of loans previously charged off	752	995	1,938	2,595
Ending balance	277,049	287,826	277,049	287,826	280,035
Provision Details [Abstract]
Provision for credit losses	0	8,000	0	16,000
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	52,088	47,319	51,640	48,977	48,977
Provision for off-balance sheet credit risk	904	(4,983)	1,352	(6,641)
Ending balance	52,992	42,336	52,992	42,336	51,640
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	24,212,884		24,212,884		24,067,999
Individually measured for impairment, recorded investment	79,327		79,327		46,725
Loans	24,292,211		24,292,211		24,114,724
Related allowance [Abstract]
Collectively measured for impairment, related allowance	273,325		273,325		279,759
Individually measured for impairment, related allowance	3,724		3,724		276
Total	277,049	287,826	277,049	287,826	280,035
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	143,505	146,267	145,153	141,232	141,232
Provision for loan losses	744	10,441	(111)	18,752
Loans charged off	(35)	(6,391)	(1,120)	(10,631)
Recoveries of loans previously charged off	184	420	476	1,384
Ending balance	144,398	150,737	144,398	150,737	145,153
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	16,167	17,790	18,046	19,762	19,762
Provision for off-balance sheet credit risk	828	(474)	(1,051)	(2,446)
Ending balance	16,995	17,316	16,995	17,316	18,046
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	14,344,025		14,344,025		15,015,489
Individually measured for impairment, recorded investment	40,157		40,157		14,647
Loans	14,384,182		14,384,182		15,030,136
Related allowance [Abstract]
Collectively measured for impairment, related allowance	140,674		140,674		144,877
Individually measured for impairment, related allowance	3,724		3,724		276
Total	144,398	150,737	144,398	150,737	145,153
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	93,724	97,479	91,072	94,718	94,718
Provision for loan losses	(8,501)	(1,042)	(6,034)	2,953
Loans charged off	(126)	(205)	(126)	(1,455)	(1,455)
Recoveries of loans previously charged off	10	24	195	40
Ending balance	85,107	96,256	85,107	96,256	91,072
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	33,461	27,865	31,959	27,439	27,439
Provision for off-balance sheet credit risk	97	(4,551)	1,599	(4,125)
Ending balance	33,558	23,314	33,558	23,314	31,959
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	5,514,516		5,514,516		5,048,547
Individually measured for impairment, recorded investment	6,925		6,925		9,905
Loans	5,521,441		5,521,441		5,058,452
Related allowance [Abstract]
Collectively measured for impairment, related allowance	85,107		85,107		91,072
Individually measured for impairment, related allowance	0		0		0
Total	85,107	96,256	85,107	96,256	91,072
Loans to individuals [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	41,365	37,877	43,810	41,173	41,173
Provision for loan losses	6,773	3,749	4,825	1,403
Loans charged off	(1,152)	(1,344)	(2,358)	(2,914)
Recoveries of loans previously charged off	558	551	1,267	1,171
Ending balance	47,544	40,833	47,544	40,833	43,810
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	2,460	1,664	1,635	1,776	1,776
Provision for off-balance sheet credit risk	(21)	42	804	(70)
Ending balance	2,439	1,706	2,439	1,706	1,635
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	4,354,343		4,354,343		4,003,963
Individually measured for impairment, recorded investment	32,245		32,245		22,173
Loans	4,386,588		4,386,588		4,026,136
Related allowance [Abstract]
Collectively measured for impairment, related allowance	47,544		47,544		43,810
Individually measured for impairment, related allowance	0		0		0
Total	$ 47,544	$ 40,833	$ 47,544	$ 40,833	$ 43,810

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Amount of allowance for credit loss on financing receivable evaluated on collective basis. Excludes financing receivable evaluated on individual basis.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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