Summary of Significant Accounting Policies - Basis of Presentation and Use of Estimates (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		12 Months Ended
	Dec. 14, 2015	Dec. 31, 2015	Nov. 30, 2017	Nov. 30, 2016	Aug. 31, 2017	Aug. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Losses from operations			$ 865	$ 1,103	$ 4,300	$ 20,600
Net cash used in operating activities			60	1,121	2,100	3,400
Gross profits (losses) on product sales			52	116	82	(4,900)
Cash and cash equivalents			3,400	$ 4,827	$ 3,582	$ 6,030
Total consideration of sale price of Taiwan headquarters building		$ 5,200
Receipt from initial installment of cash consideration for the sale of its headquarters building	$ 3,000
Second installment								$ 1,000
Second installment yet to be received							$ 1,200	$ 1,000
Deposits to purchase a portion of the equity in subsidiaries			$ 3,000
Scenario Forecast
Summary Of Significant Accounting Policies [Line Items]
Third installment							$ 1,200