Investments (Mortgage Loans Allowance for Credit Loss Rollforward by Portfolio Segment) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	$ 590	$ 353
Provision (release)	(8)	115
Adoption of new credit loss guidance	0	78
Initial credit losses on PCD loans	2	16
Charge-offs, net of recoveries	(14)	(7)
Balance, end of period	570	555
Commercial Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	252	246
Provision (release)	22	47
Adoption of new credit loss guidance	0	(118)
Initial credit losses on PCD loans	0	0
Charge-offs, net of recoveries	0	0
Balance, end of period	274	175
Residential Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	232	55
Provision (release)	(23)	62
Adoption of new credit loss guidance	0	161
Initial credit losses on PCD loans	2	16
Charge-offs, net of recoveries	(1)	(5)
Balance, end of period	210	289
Agricultural Mortgage Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance, beginning of period	106	52
Provision (release)	(7)	6
Adoption of new credit loss guidance	0	35
Initial credit losses on PCD loans	0	0
Charge-offs, net of recoveries	(13)	(2)
Balance, end of period	$ 86	$ 91