Leases - Right-of-use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Financing lease assets	$ 5,921	$ 9,718
Financing lease assets	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Operating lease right-of-use assets	$ 6,481	$ 8,678
Operating lease right-of-use assets	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Total lease assets	$ 12,402	$ 18,396
Liabilities
Financing lease liabilities - current	$ 3,222	$ 3,275
Financing lease liabilities - current	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent	us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent
Operating lease liabilities - current	$ 949	$ 1,813
Operating lease liabilities - current	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Financing lease liabilities - long-term	$ 2,552	$ 4,674
Financing lease liabilities - long-term	us-gaap:LongTermDebtAndCapitalLeaseObligations	us-gaap:LongTermDebtAndCapitalLeaseObligations
Operating lease liabilities - long-term	$ 5,532	$ 6,866
Operating lease liabilities - long-term	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Total lease liabilities	$ 12,255	$ 16,628