Leases - Schedule of Components of Lease Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Lease expense
Operating lease expense	$ 136
Sublease income	(6)
Total lease expense	130
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	131
Right-of-use assets obtained in exchange for new operating lease liabilities	598
Operating lease right-of-use assets	479
Other current lease liabilities	104
Operating lease liabilities	403
Total operating lease liabilities	$ 507
Weighted-average remaining lease term	5 years 9 months 18 days
Weighted-average discount rate	5.00%