Fair Value Measurement - Quantitative Information - Liabilities (Details) - Level 3 $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Credit derivative liabilities, net
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Internal floor (as a percent)	880.00%	880.00%
Credit derivative liabilities, net | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total liabilities carried at fair value	$ (156)	$ (154)
Credit derivative liabilities, net | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Hedge cost (as a percent)	1190.00%	800.00%
Bank profit (as a percent)	0.00%	0.00%
Credit derivative liabilities, net | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Year 1 loss estimates (as a percent)	0.00%	0.00%
Credit derivative liabilities, net | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Hedge cost (as a percent)	5320.00%	3710.00%
Bank profit (as a percent)	21130.00%	18780.00%
Credit derivative liabilities, net | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Year 1 loss estimates (as a percent)	87.00%	85.80%
Credit derivative liabilities, net | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Hedge cost (as a percent)	2180.00%	1260.00%
Bank profit (as a percent)	7220.00%	6790.00%
Credit derivative liabilities, net | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Year 1 loss estimates (as a percent)	1.90%	0.10%
Financial Guaranty Variable Interest Entities | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total liabilities carried at fair value	$ (335)	$ (289)
Financial Guaranty Variable Interest Entities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	0.60%	1.40%
Financial Guaranty Variable Interest Entities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	7.80%	8.00%
Financial Guaranty Variable Interest Entities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	4.40%	3.70%
Financial Guaranty Variable Interest Entities | CPR | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	0.90%	0.90%
Financial Guaranty Variable Interest Entities | CPR | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	25.50%	24.50%
Financial Guaranty Variable Interest Entities | CPR | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	12.30%	13.30%
Financial Guaranty Variable Interest Entities | CDR | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	1.00%	1.40%
Financial Guaranty Variable Interest Entities | CDR | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	26.90%	26.90%
Financial Guaranty Variable Interest Entities | CDR | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	6.70%	7.60%
Financial Guaranty Variable Interest Entities | Loss severity | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	45.00%	45.00%
Financial Guaranty Variable Interest Entities | Loss severity | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	100.00%	100.00%
Financial Guaranty Variable Interest Entities | Loss severity | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate	72.00%	81.60%
CLO obligations of CFEs | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total liabilities carried at fair value	$ (3,598)	$ (3,665)
Yield (as a percent)	1.60%	1.60%
CLO obligations of CFEs | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	14.20%	13.70%
CLO obligations of CFEs | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	2.20%	2.10%
Warehouse financing debt | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total liabilities carried at fair value	$ (31)	$ (23)
Warehouse financing debt | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	16.20%	12.60%
Warehouse financing debt | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	27.70%	16.00%
Warehouse financing debt | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	23.70%	13.80%
Liabilities of CIVs | Measurement Input, Revenue Multiple | Valuation, Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Market multiple-enterprise value/revenue		10.50
Other invested assets | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total assets carried at fair value	$ 5	$ 6