Summary of Accrual Activities by Components Related to Company's Restructuring Charges (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance		$ 806	$ 1,736
Restructuring charges		2,025	346
Cash payments		(1,490)	(1,212)
Non-cash write-offs and other adjustments		(65)	(64)
Accrued expense ending balance		1,276	806
Severance
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance		39	611
Restructuring charges		1,862	185
Cash payments		(962)	(692)
Non-cash write-offs and other adjustments		(63)	(65)
Accrued expense ending balance		876	39
Facility
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance		763	1,111
Restructuring charges			146
Cash payments		(373)	(503)
Non-cash write-offs and other adjustments		(2)	9
Accrued expense ending balance		388	763
Other Restructuring Charges
Restructuring Cost And Reserve [Line Items]
Accrued expense beginning balance	[1]	4	14
Restructuring charges	[1]	163	15
Cash payments	[1]	(155)	(17)
Non-cash write-offs and other adjustments	[1]		(8)
Accrued expense ending balance	[1]	$ 12	$ 4

[1] Other restructuring charges mainly related to consulting fees and relocation costs.