Goodwill and Other Intangibles (Amortized Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross Cost	$ 4,099	$ 3,874
Accumulated Amortization	1,400	1,100
Net Carrying Amount	2,699	2,774
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Cost	3,713	3,494
Accumulated Amortization	1,170	897
Net Carrying Amount	2,543	2,597
Other
Finite-Lived Intangible Assets [Line Items]
Gross Cost	386	380
Accumulated Amortization	230	203
Net Carrying Amount	$ 156	$ 177