Leases - Components of Lease Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating Lease Expense	$ 292
Finance Lease Expense:
Amortization of ROU assets	11
Interest on lease liabilities	21
Short Term Lease Expense	6
Variable Lease Expense	7
Sublease Income	(15)
Total Lease Expense	$ 322