Leases - Schedule of Future Lease Payments under Operating Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Operating Leases, Lease Payments, 2019	$ 1,160
Operating Leases, Lease Payments, 2020	4,755
Operating Leases, Lease Payments, 2021	4,790
Operating Leases, Lease Payments, 2022	4,650
Operating Leases, Lease Payments, 2023	3,263
Operating Leases, Lease Payments, Thereafter	9,947
Operating Leases, Lease Payments, Total lease payments	28,565
Less: Imputed interest	(5,495)
Present value of lease liabilities	23,070	$ 25,300
Less: Current portion of lease liabilities	(3,292)
Operating lease liabilities, net of current portion	19,778
Operating Leases, Sublease Income, 2019	(339)
Operating Leases, Sublease Income, 2020	(1,373)
Operating Leases, Sublease Income, 2021	(1,414)
Operating Leases, Sublease Income, 2022	(1,457)
Operating Leases, Sublease Income, 2023	(123)
Operating Leases, Sublease Income, Total lease payments	(4,706)
Operating Leases, Net, 2019	821
Operating Leases, Net, 2020	3,382
Operating Leases, Net, 2021	3,376
Operating Leases, Net, 2022	3,193
Operating Leases, Net, 2023	3,140
Operating Leases, Net, Thereafter	9,947
Operating Leases, Net, Total lease payments	23,859
Finance Leases, Lease Payments, 2019	120
Finance Leases, Lease Payments, 2020	270
Finance Leases, Lease Payments, Total lease payments	390
Less: Imputed interest	(19)
Present value of lease liabilities	371
Less: Current portion of lease liabilities	(353)		$ (523)
Finance lease liabilities, net of current portion	$ 18		$ 258