Leases (Lease and Other Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Lease, Cost	$ 47	$ 45
Short-term Lease, Cost	13	12
Sublease Income	(3)	(4)
Lease, Cost	57	53
Operating Lease, Payments	44	44
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 323	$ 0
Operating Lease, Weighted Average Remaining Lease Term	7 years 2 months 12 days	6 years 6 months
Weighted Average Discount Rate, Percent	3.57%	3.97%
Other Noncurrent Assets [Member]
Operating Lease, Right-of-Use Asset	$ 915	$ 575
Other Current Liabilities [Member]
Operating Lease, Liability, Current	195	158
Other Noncurrent Liabilities [Member]
Operating Lease, Liability, Noncurrent	$ 801	$ 482