Leases Lease Cost (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating Lease, Cost	$ 73
Short-term Lease, Cost	23
Lease, Cost	96
Operating Lease, Payments	40
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 61
Operating Lease, Weighted Average Remaining Lease Term	7 years
Operating Lease, Weighted Average Discount Rate, Percent	4.60%