Leases (Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease ROU assets	$ 937	$ 577
Operating lease ROU assets, Balance Sheet clarification	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease liabilities	$ 1,033	$ 650
Operating lease liabilities, Balance Sheet clarification	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent