Leases - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Options to extend term	12 years
Assets recorded under finance leases	$ 49
Finance lease asset, accumulated depreciation	4
Operating lease not yet commenced	$ 35
Minimum
Lessee, Lease, Description [Line Items]
Lease renewal term	1 year
Options to terminate term	1 month
Operating leases not yet commenced lease term	2 years
Maximum
Lessee, Lease, Description [Line Items]
Lease renewal term	15 years
Options to terminate term	2 years
Operating leases not yet commenced lease term	15 years