Summary of Significant Accounting Policies - Summary of Impact of the Adoption of Topic 842 (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Other non-current assets	$ 114		$ 50
Lease Liabilities:
Current operating lease liabilities	289
Non-current operating lease liabilities	4,867
Accrued and other current liabilities	12,676		9,576
Other non-current liabilities	$ 38		$ 72
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Other non-current assets		$ 741
Lease Liabilities:
Current operating lease liabilities		339
Non-current operating lease liabilities		465
Accrued and other current liabilities		9,535
ASU 2016-02 | Effect of the Adoption of Topic 842
Summary Of Significant Accounting Policies [Line Items]
Other non-current assets		691
Lease Liabilities:
Current operating lease liabilities		339
Non-current operating lease liabilities		465
Accrued and other current liabilities		(41)
Other non-current liabilities		$ (72)