Investments (Mortgage Loans Allowance for Credit Loss Rollforward by Portfolio Segment) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	$ 590	$ 353
Provision (release)	(15)	102
Adoption of credit loss guidance	0	78
Initial credit losses on PCD loans (1)	3	16
Charge-offs, net of recoveries	15	29
Balance, end of period	563	520
Commercial Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	252	246
Provision (release)	22	83
Adoption of credit loss guidance	0	(118)
Initial credit losses on PCD loans (1)	0	0
Charge-offs, net of recoveries	0	0
Balance, end of period	274	211
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	232	55
Provision (release)	(37)	13
Adoption of credit loss guidance	0	161
Initial credit losses on PCD loans (1)	3	16
Charge-offs, net of recoveries	2	27
Balance, end of period	196	218
Agricultural Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	106	52
Provision (release)	0	6
Adoption of credit loss guidance	0	35
Initial credit losses on PCD loans (1)	0	0
Charge-offs, net of recoveries	13	2
Balance, end of period	$ 93	$ 91