Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Allowance for loan and lease losses	$ 411	$ 422
Employee benefits	209	166
Net unrealized securities losses	1,045	1,612
Federal net operating losses and credits	303	3
Non-tax accruals	109	142
Operating lease liabilities	127	136
State net operating losses and credits	20	1
Partnership investments	79	78
Other	149	148
Gross deferred tax assets	2,452	2,708
Less: Valuation Allowance	15	12
Total deferred tax assets	2,437	2,696
Leasing transactions	378	446
State taxes	76	77
Operating lease right-of-use assets	114	119
Goodwill	178	157
Other	68	82
Total deferred tax liabilities	814	881
Net deferred tax assets (liabilities)	$ 1,623	$ 1,815