Closed Block (Liabilities and Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Closed Block Liabilities
Future policy benefits	$ 39,037	$ 39,379
Other policy-related balances	331	423
Policyholder dividends payable	433	432
Policyholder dividend obligation	2,798	2,020	$ 428
Deferred income tax liability	101	79
Other liabilities	128	81
Total closed block liabilities	42,828	42,414
Assets Designated to the Closed Block
Fixed maturity securities available-for-sale, at estimated fair value	26,576	25,977
Equity securities, at estimated fair value	45	49
Contractholder-directed equity securities and fair value option securities, at estimated fair value	53	53
Mortgage loans	6,985	7,052
Policy loans	4,419	4,489
Real estate and real estate joint ventures	565	544
Other invested assets	724	314
Total investments	39,367	38,478
Cash and cash equivalents	111	448
Accrued investment income	409	419
Premiums, reinsurance and other receivables	65	75
Current income tax recoverable	13	91
Total assets designated to the closed block	39,965	39,511
Excess of closed block liabilities over assets designated to the closed block	2,863	2,903
AOCI:
Unrealized investment gains (losses), net of income tax	3,039	2,453
Unrealized gains (losses) on derivatives, net of income tax	257	97
Allocated to policyholder dividend obligation, net of income tax	(2,210)	(1,596)
Total amounts included in AOCI	1,086	954
Maximum future earnings to be recognized from closed block assets and liabilities	$ 3,949	$ 3,857