Leases - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term - Operating leases (in years)	5 years
Termination period	1 year
Operating lease not yet commenced	$ 1
Minimum
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term - Operating leases (in years)	1 year
Maximum
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term - Operating leases (in years)	24 years 3 months 18 days
Extension period	20 years