Leases - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Maximum potential loss of lease agreement	$ 16
Operating lease not yet commenced	$ 16
Expected commencement period of leases not yet commenced	18 months
Minimum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	1 year
Renewal term of lease yet to be commenced	3 years
Maximum
Lessee, Lease, Description [Line Items]
Operating lease renewal term	40 years
Renewal term of lease yet to be commenced	10 years