Allowance for Credit Losses - Schedule of Activity in the Allowance for Credit Losses by Loan Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	$ 457,063	$ 437,069	$ 436,603	$ 427,265
Other adjustments	(88)	30	96	(20)
Charge-offs	(28,846)	(31,018)	(64,790)	(89,615)
Recoveries	4,291	4,283	14,255	11,144
Provision for credit losses - Other	21,771		68,027
Provision for credit losses	21,800	6,799	68,000	68,389
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		15,547		15,547
Initial allowance for credit losses recognized on PCD assets acquired during the period		3,004		3,004
Allowance for credit losses at period end	454,191	435,714	454,191	435,714
Individually measured	39,498	27,630	39,498	27,630
Collectively measured	414,693	408,084	414,693	408,084
Individually measured	124,966	124,586	124,966	124,586
Collectively measured	51,808,923	46,804,823	51,808,923	46,804,823
Loans held at fair value	129,593	138,038	129,593	138,038
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	194,568	181,991	175,837	169,604
Other adjustments	0	0	0	0
Charge-offs	(21,597)	(22,975)	(37,467)	(43,774)
Recoveries	1,449	649	4,124	2,078
Provision for credit losses - Other	15,056		46,982
Provision for credit losses		7,128		38,885
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		2,967		2,967
Initial allowance for credit losses recognized on PCD assets acquired during the period		1,838		1,838
Allowance for credit losses at period end	189,476	171,598	189,476	171,598
Individually measured	29,747	21,573	29,747	21,573
Collectively measured	159,729	150,025	159,729	150,025
Individually measured	66,576	63,826	66,576	63,826
Collectively measured	16,477,766	15,183,867	16,477,766	15,183,867
Loans held at fair value	0	0	0	0
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	224,358	223,728	222,856	223,853
Other adjustments	0	0	0	0
Charge-offs	(144)	(95)	(6,309)	(21,090)
Recoveries	241	30	263	151
Provision for credit losses - Other	6,022		13,667
Provision for credit losses		(4,162)		16,587
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		10,540		10,540
Initial allowance for credit losses recognized on PCD assets acquired during the period		1,103		1,103
Allowance for credit losses at period end	230,477	231,144	230,477	231,144
Individually measured	9,688	5,958	9,688	5,958
Collectively measured	220,789	225,186	220,789	225,186
Individually measured	28,203	42,071	28,203	42,071
Collectively measured	13,591,004	12,751,346	13,591,004	12,751,346
Loans held at fair value	0	0	0	0
Home  Equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	9,221	7,242	8,943	7,116
Other adjustments	0	0	0	0
Charge-offs	(27)	0	(138)	(74)
Recoveries	104	101	350	165
Provision for credit losses - Other	(69)		74
Provision for credit losses		134		270
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		1,344		1,344
Initial allowance for credit losses recognized on PCD assets acquired during the period		2		2
Allowance for credit losses at period end	9,229	8,823	9,229	8,823
Individually measured	0	50	0	50
Collectively measured	9,229	8,773	9,229	8,773
Individually measured	1,295	1,122	1,295	1,122
Collectively measured	482,907	425,921	482,907	425,921
Loans held at fair value	0	0	0	0
Residential Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	11,455	8,773	10,335	13,133
Other adjustments	0	0	0	0
Charge-offs	(26)	0	(26)	(61)
Recoveries	1	5	139	15
Provision for credit losses - Other	583		1,565
Provision for credit losses		268		(4,041)
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		638		638
Initial allowance for credit losses recognized on PCD assets acquired during the period		61		61
Allowance for credit losses at period end	12,013	9,745	12,013	9,745
Individually measured	60	48	60	48
Collectively measured	11,953	9,697	11,953	9,697
Individually measured	28,854	17,565	28,854	17,565
Collectively measured	3,985,423	3,232,435	3,985,423	3,232,435
Loans held at fair value	129,593	138,038	129,593	138,038
Premium Finance Receivables
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	16,612	14,746	17,820	13,069
Other adjustments	(88)	30	96	(20)
Charge-offs	(6,878)	(7,794)	(20,350)	(24,218)
Recoveries	2,459	3,477	9,281	8,667
Provision for credit losses - Other	(156)		5,102
Provision for credit losses		3,284		16,245
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		0		0
Initial allowance for credit losses recognized on PCD assets acquired during the period		0		0
Allowance for credit losses at period end	11,949	13,743	11,949	13,743
Individually measured	0	0	0	0
Collectively measured	11,949	13,743	11,949	13,743
Individually measured	0	0	0	0
Collectively measured	17,124,845	15,128,580	17,124,845	15,128,580
Loans held at fair value	0	0	0	0
Consumer and Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	849	589	812	490
Other adjustments	0	0	0	0
Charge-offs	(174)	(154)	(500)	(398)
Recoveries	37	21	98	68
Provision for credit losses - Other	335		637
Provision for credit losses		147		443
Provision for credit losses - Day 1 on non-PCD assets acquired during the period		58		58
Initial allowance for credit losses recognized on PCD assets acquired during the period		0		0
Allowance for credit losses at period end	1,047	661	1,047	661
Individually measured	3	1	3	1
Collectively measured	1,044	660	1,044	660
Individually measured	38	2	38	2
Collectively measured	146,978	82,674	146,978	82,674
Loans held at fair value		$ 0		$ 0