Summary of Significant Accounting Policies - Impact of Adopting Topic 842 on Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Operating lease right-of-use assets	$ 8,134	$ 8,641
Current liabilities:
Other accrued liabilities	5,704	1,482	$ 1,845
Current portion of operating lease liabilities	1,431	1,058
Operating lease liabilities, net of current portion	11,095	11,776
Other long-term liabilities	$ 0	0	3,830
Total		14,316	$ 5,675
Topic 842
Assets
Operating lease right-of-use assets		8,641
Current liabilities:
Other accrued liabilities		(363)
Current portion of operating lease liabilities		1,058
Operating lease liabilities, net of current portion		11,776
Other long-term liabilities		(3,830)
Total		$ 8,641