Other Long-Term Liabilities - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Other Liabilities, Noncurrent [Line Items]
Deferred rent and other facility costs	$ 1,880,000	$ 6,837,000
Deferred payment arrangements value	2,000,000.0	3,100,000
Funds received from investor	2,800,000
Long-term lease incentive liability	$ 0	2,300,000
Minimum
Other Liabilities, Noncurrent [Line Items]
Leasehold improvements and long-term liability amortization period (in years)	5 years
Maximum
Other Liabilities, Noncurrent [Line Items]
Leasehold improvements and long-term liability amortization period (in years)	10 years
Asset Retirement Obligation
Other Liabilities, Noncurrent [Line Items]
Deferred rent and other facility costs	$ 2,000,000.0	$ 1,900,000