Lease Cost (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease cost	$ 481
Amortization of right-of-use assets	37
Interest on lease liabilities	24
Short-term lease cost	85
Total lease cost	627
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle in period of adoption	$ 2,300