Closed Block (Liabilities and Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Closed Block Liabilities
Future policy benefits	$ 38,758	$ 39,379
Other policy-related balances	321	423
Policyholder dividends payable	337	432
Policyholder dividend obligation	2,969	2,020	$ 428	$ 2,121
Deferred income tax liability	130	79
Other liabilities	172	81
Total closed block liabilities	42,687	42,414
Assets Designated to the Closed Block
Fixed maturity securities available-for-sale, at estimated fair value	27,186	25,977
Equity securities, at estimated fair value	24	49
Contractholder-directed equity securities and fair value option securities, at estimated fair value	0	53
Mortgage loans	6,807	7,052
Policy loans	4,355	4,489
Real estate and real estate joint ventures	559	544
Other invested assets	468	314
Total investments	39,399	38,478
Cash and cash equivalents	0	448
Accrued investment income	402	419
Premiums, reinsurance and other receivables	50	75
Current income tax recoverable	28	91
Total assets designated to the closed block	39,879	39,511
Excess of closed block liabilities over assets designated to the closed block	2,808	2,903
AOCI:
Unrealized investment gains (losses), net of income tax	3,524	2,453
Unrealized gains (losses) on derivatives, net of income tax	23	97
Allocated to policyholder dividend obligation, net of income tax	(2,346)	(1,596)
Total amounts included in AOCI	1,201	954
Maximum future earnings to be recognized from closed block assets and liabilities	$ 4,009	$ 3,857