Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019
Operating Leases:
ROU assets associated with operating leases	$ 32,739	$ 34,376	$ 35,371
Finance Lease:
Property, plant and equipment, gross	104,109
Accumulated depreciation	(85,967)
Property, plant and equipment, net	$ 18,142
Weighted average remaining lease term (in years)
Operating leases	9 years 11 months 26 days
Finance lease	2 years 11 months 19 days
Weighted average discount rate
Operating leases	4.48%
Finance lease	5.46%