Leases - Schedule of Operating Leases (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Lease cost	$ 16	$ 34
Variable lease cost	10	23
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for leases	15	31
Lease assets obtained in exchange for new lease liabilities	$ 23	$ 152
Weighted average remaining lease term	8 years 6 months	8 years 6 months
Weighted average discount rate	3.40%	3.40%