Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Operating lease right-of-use assets, net of amortization	$ 568	$ 0
Other current liabilities	178
Long-term operating lease liabilities	403	$ 0
Total operating lease liabilities	581
Finance leases, net of amortization (within property, plant & equipment)	122
Current portion of long-term debt	32
Long-term debt	91
Total finance lease liabilities	$ 123
Operating leases, weighted average remaining lease term	5 years 2 months 12 days
Finance leases, weighted average remaining lease term	4 years 7 months 6 days
Operating leases, weighted average discount rate	3.50%
Finance leases, weighted average discount rate	3.70%