Fair Value Measurements - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, carrying value	$ 76,290		$ 74,111
Assets, fair value	49,247		49,779
Liabilities, carrying value	58,428		55,555
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	2,174		1,805
Significant Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	43,523		43,910
Carrying Amount | Significant Unobservable Inputs (Level 3) | Other policyholder funds and benefits payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, carrying value	685		701
Carrying Amount | Significant Unobservable Inputs (Level 3) | Mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, carrying value	5,106		4,493
Carrying Amount | Significant Observable Inputs (Level 2) | Senior notes [2]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, carrying value	3,853		3,262
Carrying Amount | Significant Observable Inputs (Level 2) | Junior subordinated debentures [2]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, carrying value	1,090		1,090
Fair Value | Significant Unobservable Inputs (Level 3) | Other policyholder funds and benefits payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	688		703
Fair Value | Significant Unobservable Inputs (Level 3) | Mortgage loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	5,332		4,792
Fair Value | Significant Observable Inputs (Level 2) | Senior notes [2]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	4,707		4,363
Fair Value | Significant Observable Inputs (Level 2) | Junior subordinated debentures [2]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, fair value	1,107		1,107
Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 26	$ 24	$ 38	$ 38	$ 43	$ 0