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Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Estimated Future Premium Payments Minimum Discounted Rate	2.30%
Estimated Future Premium Payments Maximum Discounted Rate	3.50%
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	$ 6,194	$ 5,884	$ 6,376	$ 6,207
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	(145)	130
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	49	(377)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(86)	(76)
Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	76	66	78	72
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	(2)	(6)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	0
Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	1	3	1	3
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	0	0
Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	2,948	2,932	2,998	3,108
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	9	88
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	24	(190)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(84)	(74)
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	65	77	84	66
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	(17)	12
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(2)	(1)
Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability	3,103	2,806	$ 3,215	$ 2,957
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings	(138)	30
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	$ 26	$ (181)

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