Fair Value Measurement - Quantitative Information - Assets (Details) - Level 3 $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Obligations of state and political subdivisions | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 72	$ 101
Obligations of state and political subdivisions | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	4.40%	6.40%
Obligations of state and political subdivisions | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	24.50%	33.40%
Obligations of state and political subdivisions | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	6.20%	12.80%
RMBS | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 216	$ 255
RMBS | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	3.80%	3.70%
RMBS | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	5.60%	5.90%
RMBS | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	4.50%	4.50%
Life insurance transactions | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 367
Yield (as a percent)	5.00%
CLO contracts | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 458	$ 532
Others | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 38	$ 41
Others | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	3.20%	2.60%
Others | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	7.90%	9.00%
Others | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	7.90%	9.00%
Financial Guarantee Variable Interest Entities | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 260	$ 296
Financial Guarantee Variable Interest Entities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	1.40%	1.90%
Financial Guarantee Variable Interest Entities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	8.00%	6.00%
Financial Guarantee Variable Interest Entities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	4.60%	4.80%
Corporate securities | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value		$ 30
Yield (as a percent)		42.00%
Other | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 23	$ 52
Fair value inputs term	10 years	10 years
Other | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	2.70%	3.40%
Other | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	3.30%	4.20%
Other | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	3.00%	3.80%
Other invested assets | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 6	$ 5
Life insurance transactions | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value		$ 367
Life insurance transactions | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)		5.20%
Assets of Consolidated Investment Vehicles | Equity securities and warrants | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 239	$ 2
Yield (as a percent)	7.70%	9.70%
Assets of Consolidated Investment Vehicles | Corporate securities | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	16.40%
CPR | RMBS | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	0.00%	0.40%
CPR | RMBS | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	22.70%	30.00%
CPR | RMBS | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	10.40%	7.10%
CPR | Financial Guarantee Variable Interest Entities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	0.90%	0.90%
CPR | Financial Guarantee Variable Interest Entities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	24.50%	19.00%
CPR | Financial Guarantee Variable Interest Entities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	13.30%	9.40%
CDR | RMBS | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	1.40%	1.50%
CDR | RMBS | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	12.00%	9.90%
CDR | RMBS | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	5.90%	6.00%
CDR | Financial Guarantee Variable Interest Entities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	1.40%	1.90%
CDR | Financial Guarantee Variable Interest Entities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	26.90%	26.60%
CDR | Financial Guarantee Variable Interest Entities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	7.60%	6.00%
Loss severity | RMBS | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	50.00%	45.00%
Loss severity | RMBS | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	125.00%	125.00%
Loss severity | RMBS | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	84.90%	83.60%
Loss severity | Financial Guarantee Variable Interest Entities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	45.00%	45.00%
Loss severity | Financial Guarantee Variable Interest Entities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	100.00%	100.00%
Loss severity | Financial Guarantee Variable Interest Entities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	81.60%	81.50%
Discount rate | CLO contracts | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	0.00%	0.10%
Discount rate | CLO contracts | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	2.90%	3.10%
Discount rate | CLO contracts | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	1.80%	1.90%
Discount rate | Corporate securities | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	14.70%
Discount rate | Corporate securities | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	21.40%
Discount rate | Corporate securities | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	17.80%
Discount rate | Assets of Consolidated Investment Vehicles | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset, fair value	$ 91
Discount rate | Assets of Consolidated Investment Vehicles | Equity securities and warrants | Minimum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	14.70%
Discount rate | Assets of Consolidated Investment Vehicles | Equity securities and warrants | Maximum | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	23.90%
Discount rate | Assets of Consolidated Investment Vehicles | Equity securities and warrants | Weighted Average | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Yield (as a percent)	21.60%
Multiple enterprise/revenue value | Equity securities and warrants | Valuation, Income Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Conditional prepayment rate (as a percent)	185.00%
Multiple enterprise/revenue value | Assets of Consolidated Investment Vehicles | Valuation, Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Market multiple-enterprise value/revenue	1.10000
Measurement Input, EBITDA Multiple | Assets of Consolidated Investment Vehicles | Minimum | Valuation, Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Market multiple - enterprise value/EBITDA	3.00000
Measurement Input, EBITDA Multiple | Assets of Consolidated Investment Vehicles | Maximum | Valuation, Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Market multiple - enterprise value/EBITDA	10.50
Measurement Input, EBITDA Multiple | Assets of Consolidated Investment Vehicles | Weighted Average | Valuation, Market Approach
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Market multiple - enterprise value/EBITDA	8.95000