Summary of Significant Accounting Policies - Allowance For Credit Loss (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Investments	$ 142	$ 103
Premium installment receivables	153	91	$ 91
Reinsurance recoverables	74	74
Other assets	23	18
Assets	392	286
Commitments to fund mortgage loans, bank loans and agent loans	1	3
Liabilities	1	3
Total	393	289
Fixed income securities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Fixed income securities	3	0	0
Mortgage loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance credit losses	67	45	$ 3
Bank loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance credit losses	67	53
Agent loans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance credit losses	$ 5	$ 5