Accounting Policies - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cumulative effect of new accounting principle in period of adoption, net of tax	$ 11,101		$ 10,098	$ 10,077
RETAINED EARNINGS
Accounting Policies [Abstract]
Cumulative effect of new accounting principle in period of adoption, net of tax	$ 1,051	$ 469	$ 48	$ 27	$ 73	$ 67
Cumulative Effect Of New Accounting Principle In Period Of Adoption, Tax						1
Cumulative Effect, Period of Adoption, Adjustment | RETAINED EARNINGS
Accounting Policies [Abstract]
Cumulative effect of new accounting principle in period of adoption, net of tax						$ 3