Leases (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Leases [Abstract]
Operating Lease Expense	$ 115	$ 108	$ 230	$ 216
short term leases and variable leases costs	35	$ 32	70	67
Operating Lease Payments			162	147
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			209	$ 164
Operating Lease, Right-of-Use Asset	$ 1,288		$ 1,288		$ 1,214
Included within other noncurrent assets	us-gaap:OtherAssets		us-gaap:OtherAssets		us-gaap:OtherAssets
Operating lease liabilities	$ 258		$ 258		$ 235
Current portion included within accounts payable and accrued liabilities	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent		us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent		us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Noncurrent portion of operating lease liability	$ 1,166		$ 1,166		$ 1,110
Long-term portion included within other long-term liabilities	OTHER LONG-TERM LIABILITIES		OTHER LONG-TERM LIABILITIES		OTHER LONG-TERM LIABILITIES
Total Operating Lease Liability	$ 1,424		$ 1,424		$ 1,345
Weighted average remaining operating lease term (in years)	6 years		6 years		6 years 4 months 24 days
Weighted average discount rate - operating leases (percentage)	3.60%		3.60%		3.90%
Finance Lease Liabilities	$ 64		$ 64		$ 63
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
Six months ended December 31, 2021	165		165
2022	320		320
2023	299		299
2024	250		250
2025	199		199
Thereafter	421		421
Undiscounted lease cash flow commitments	1,654		1,654
Reconciling impact from discounting	$ (230)		$ (230)