Leases - Components of Net Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Finance leases
Amortization of right-of-use assets	$ 481	$ 642	$ 978	$ 1,145
Interest on lease liabilities	65	80	132	161
Operating lease cost	1,289	1,289	2,579	2,589
Short-term lease cost	111	123	220	203
Variable lease cost	332	346	679	690
Sublease income	(63)	(82)	(162)	(169)
Net lease cost	$ 2,215	$ 2,398	$ 4,426	$ 4,619