Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Lessor, operating lease, term of contract	15 years 3 months
Operating lease cost	$ 3.7	$ 3.8
Minimum
Lessee, Lease, Description [Line Items]
Operating​ lease​, remaining ​lease ​term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating​ lease​, remaining ​lease ​term	15 years 3 months 18 days