Recently Issued Accounting Standards - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses	$ 1,486	$ 1,596
Operating lease right-of-use assets	20,846	22,304
Assets	1,120,649	1,129,755
Other long-term liabilities	2,125	1,737
Current portion of operating lease obligations	2,064	1,554
Obligations under operating leases, net of current portion	19,952	21,533
Liabilities	$ 887,853	$ 903,186