Fair Value Measurements - Nonrecurring Fair Value Inputs (Details) $ in Millions	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measured at fair value	$ 5,431	$ 2,271
Loans and leases, measured at fair value	3,757	3,498
Nonrecurring \| Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measured at fair value	196		$ 229
Nonrecurring \| Level 3 \| Pricing model
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measured at fair value	$ 196	$ 0
Implied yield \| Nonrecurring \| Level 3 \| Pricing model \| Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.12
Implied yield \| Nonrecurring \| Level 3 \| Pricing model \| Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.38