Leases - Schedule of Future Lease Payments under Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
Operating Leases, Lease Payments, 2019	$ 3,465
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	9,948
Operating Leases, Lease Payments, Total lease payments	30,871
Less: Interest	(6,285)
Present value of lease liabilities	24,586	$ 25,300
Less: Current portion of lease liabilities	(3,122)
Operating lease liabilities, net of current portion	21,464
Operating Leases, Sublease Income, 2019	(882)
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	(5,249)
Operating Leases, Net, 2019	2,583
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	9,948
Operating Leases, Net, Total lease payments	25,622
Finance Leases, Lease Payments, 2019	411
Finance Leases, Lease Payments, 2020	270
Finance Leases, Lease Payments, Total lease payments	681
Less: Interest	(47)
Present value of lease liabilities	634
Less: Current portion of lease liabilities	(476)		$ (523)
Finance lease liabilities, net of current portion	$ 158		$ 258