Leases - Narrative (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) lease
Lessee, Lease, Description [Line Items]
Number of noncancellable operating leases | lease	2
Short-term lease cost	$ 328
Short-term Lease Terminated in March 2019
Lessee, Lease, Description [Line Items]
Short-term lease cost	$ 200
Emeryville lease
Lessee, Lease, Description [Line Items]
Length of each lease renewal	5 years