Operating Leases - Lease Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 27
Short-term lease cost	1
Variable lease cost	4
Sublease income	0
Total lease cost	32
Operating cash flows from operating leases	26
Right-of-use assets obtained in exchange for lease obligations	$ 25
Weighted average remaining lease term, Operating leases	9 years 7 months 9 days
Weighted average discount rate, Operating leases	3.00%