Restricted Net Assets Restricted Net Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted net assets in the Company's consolidated subsidiaries	$ 21,563	$ 20,932
Cash restricted in China as a result of ongoing litigation and unfulfilled government grants
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted net assets in the Company's consolidated subsidiaries	11,497	11,018
China earnings restricted to fund statutory common reserves in China as well as allocate a discretional portion of the Chinese subsidiaries' after-tax profits to their staff welfare and bonus fund
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted net assets in the Company's consolidated subsidiaries	9,140	9,005
Loan agreements in Japan requiring local subsidiaries to maintain minimum net asset levels
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted net assets in the Company's consolidated subsidiaries	$ 926	$ 909