Variable Interest Entities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) entity limitedPartnership	Dec. 31, 2019 USD ($) entity
Variable Interest Entity [Line Items]
Long-term investments	$ 23,262	$ 21,542
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Number of VIEs | entity
Variable Interest Entity, Not Primary Beneficiary | Securities Limited Partnerships and Real Estate Limited Partnerships
Variable Interest Entity [Line Items]
Number of limited partnerships defined as variable interest entities | limitedPartnership	150
Long-term investments	$ 2,100
Commitments to contribute additional cash, amount	1,900
Maximum exposure to loss related to arrangements with variable interest entity	$ 4,000
Variable Interest Entity, Not Primary Beneficiary | Securities Limited Partnerships and Real Estate Limited Partnerships | Maximum
Variable Interest Entity [Line Items]
Non-controlling interest percentage	15.00%
Variable Interest Entity, Not Primary Beneficiary | Other Asset-Backed and Corporate Securities
Variable Interest Entity [Line Items]
Maximum exposure to loss related to arrangements with variable interest entity	$ 500
Carrying values	500
Variable Interest Entity, Not Primary Beneficiary | Various Other Variable Interest Entities
Variable Interest Entity [Line Items]
Maximum exposure to loss related to arrangements with variable interest entity
Carrying values