v3.26.1
Fair Value Measurement - Quantitative Information about Level 3 Fair Value Measurements (Details)
$ in Millions
Mar. 31, 2026
USD ($)
Dec. 31, 2025
USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 90,620 $ 91,051
Recurring    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 90,620 91,051
Recurring | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 284 148
Retained interests in securitizations 27 28
Net derivative assets (liabilities) 88 110
Total RMBS    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 69,613 69,728
Total RMBS | Recurring    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 69,613 69,728
Total RMBS | Recurring | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 154 126
CMBS | Recurring    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value 7,471 7,892
CMBS | Recurring | Level 3    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Fair Value $ 130 $ 22
Measurement input, yield | Total RMBS | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.05 0.05
Measurement input, yield | Total RMBS | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.10 0.10
Measurement input, yield | Total RMBS | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.06 0.06
Measurement input, yield | CMBS | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.04 0.04
Measurement input, yield | CMBS | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.05 0.04
Measurement input, yield | CMBS | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.05 0.04
Voluntary prepayment rate | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.09 0.08
Voluntary prepayment rate | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.09 0.08
Voluntary prepayment rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0 0
Voluntary prepayment rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.16 0.16
Voluntary prepayment rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.07 0.07
Default rate | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.01 0.01
Default rate | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.01 0.01
Default rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0 0
Default rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.06 0.06
Default rate | Total RMBS | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.01 0.01
Loss severity | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.65 0.49
Loss severity | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.65 0.49
Loss severity | Total RMBS | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.25 0.25
Loss severity | Total RMBS | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.75 0.75
Loss severity | Total RMBS | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Securities available-for-sale, measurement input 0.55 0.55
Life of receivables (months) | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input, life of receivables 33 months 35 months
Life of receivables (months) | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input, life of receivables 64 months 64 months
Discount rate | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.05 0.05
Discount rate | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Retained interests, measurement input 0.12 0.12
Measurement input, swap rates | Recurring | Level 3 | Discounted cash flows | Minimum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Net derivative assets (liabilities), measurement input 0.04 0.03
Measurement input, swap rates | Recurring | Level 3 | Discounted cash flows | Maximum    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Net derivative assets (liabilities), measurement input 0.04 0.04
Measurement input, swap rates | Recurring | Level 3 | Discounted cash flows | Weighted average    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Net derivative assets (liabilities), measurement input 0.04 0.03