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Loans, Leases and Allowance for Credit Losses - Disaggregation of the Company's ACL on Funded Loans and Loan Balances (Details) - USD ($) $ in Millions	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	$ 55,531.0		$ 52,817.0
Individually Evaluated for Credit Loss	408.0		859.0
Loans HFI, net of deferred fees and costs	55,939.0		53,676.0
Collectively Evaluated for Credit Loss	344.0		304.5
Individually Evaluated for Credit Loss	50.7		69.3
Total	394.7	$ 388.6	373.8	$ 351.8	$ 340.3	$ 336.7
Warehouse lending
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	8,574.0		8,207.0
Individually Evaluated for Credit Loss	0.0		0.0
Loans HFI, net of deferred fees and costs	8,574.0		8,207.0
Collectively Evaluated for Credit Loss	5.9		6.4
Individually Evaluated for Credit Loss	0.0		0.0
Total	5.9	6.3	6.4	6.5	7.3	5.8
Municipal & nonprofit
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	1,629.0		1,615.0
Individually Evaluated for Credit Loss	5.0		5.0
Loans HFI, net of deferred fees and costs	1,634.0		1,620.0
Collectively Evaluated for Credit Loss	10.8		14.1
Individually Evaluated for Credit Loss	0.5		0.6
Total	11.3	14.8	14.7	14.0	13.9	14.7
Tech & innovation
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	3,576.0		3,283.0
Individually Evaluated for Credit Loss	33.0		100.0
Loans HFI, net of deferred fees and costs	3,609.0		3,383.0
Collectively Evaluated for Credit Loss	40.0		33.6
Individually Evaluated for Credit Loss	5.7		22.3
Total	45.7	44.9	55.9	45.0	48.0	42.1
Equity fund resources
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	857.0		884.0
Individually Evaluated for Credit Loss	0.0		0.0
Loans HFI, net of deferred fees and costs	857.0		884.0
Collectively Evaluated for Credit Loss	2.2		1.6
Individually Evaluated for Credit Loss	0.0		0.0
Total	2.2	1.4	1.6	1.7	1.2	1.3
Other commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	10,433.0		9,047.0
Individually Evaluated for Credit Loss	41.0		128.0
Loans HFI, net of deferred fees and costs	10,474.0		9,175.0
Collectively Evaluated for Credit Loss	101.2		75.5
Individually Evaluated for Credit Loss	8.0		2.3
Total	109.2	91.7	77.8	84.3	67.1	81.4
CRE - owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	1,595.0		1,658.0
Individually Evaluated for Credit Loss	3.0		17.0
Loans HFI, net of deferred fees and costs	1,598.0		1,675.0
Collectively Evaluated for Credit Loss	3.9		3.4
Individually Evaluated for Credit Loss	0.0		0.0
Total	3.9	3.7	3.4	5.0	6.2	6.0
Hotel franchise finance
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	3,929.0		3,786.0
Individually Evaluated for Credit Loss	0.0		29.0
Loans HFI, net of deferred fees and costs	3,929.0		3,815.0
Collectively Evaluated for Credit Loss	36.0		35.3
Individually Evaluated for Credit Loss	0.0		0.0
Total	36.0	33.2	35.3	39.6	35.8	33.4
Other CRE - non-owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	6,371.0		5,830.0
Individually Evaluated for Credit Loss	181.0		512.0
Loans HFI, net of deferred fees and costs	6,552.0		6,342.0
Collectively Evaluated for Credit Loss	93.1		90.3
Individually Evaluated for Credit Loss	31.9		44.1
Total	125.0	138.1	134.4	104.5	104.7	96.0
Residential
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	13,166.0		12,961.0
Individually Evaluated for Credit Loss	0.0		0.0
Loans HFI, net of deferred fees and costs	13,166.0		12,961.0
Collectively Evaluated for Credit Loss	19.9		19.7
Individually Evaluated for Credit Loss	0.0		0.0
Total	19.9	19.7	19.7	18.8	22.1	23.1
Residential EBO
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	929.0		972.0
Individually Evaluated for Credit Loss	0.0		0.0
Loans HFI, net of deferred fees and costs	929.0		972.0
Collectively Evaluated for Credit Loss	0.0		0.0
Individually Evaluated for Credit Loss	0.0		0.0
Total	0.0	0.0	0.0	0.0	0.0	0.0
Construction and land development
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	4,335.0		4,401.0
Individually Evaluated for Credit Loss	143.0		67.0
Loans HFI, net of deferred fees and costs	4,478.0		4,468.0
Collectively Evaluated for Credit Loss	29.0		21.3
Individually Evaluated for Credit Loss	4.6		0.0
Total	33.6	32.0	21.3	29.9	31.9	30.4
Other
Financing Receivable, Allowance for Credit Loss [Line Items]
Collectively Evaluated for Credit Loss	137.0		173.0
Individually Evaluated for Credit Loss	2.0		1.0
Loans HFI, net of deferred fees and costs	139.0		174.0
Collectively Evaluated for Credit Loss	2.0		3.3
Individually Evaluated for Credit Loss	0.0		0.0
Total	$ 2.0	$ 2.8	$ 3.3	$ 2.5	$ 2.1	$ 2.5