Variable Interest Entities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) limitedPartnership entity	Dec. 31, 2019 USD ($) entity
Variable Interest Entity [Line Items]
Long-term investments	$ 21,952	$ 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]
Maximum exposure to loss related to arrangements with variable interest entity	$ 3,900
Number of limited partnerships defined as variable interest entities | limitedPartnership	150
Long-term investments	$ 2,000
Commitments to contribute additional cash, amount	$ 1,900
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	$ 700
Carrying values	700
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