Cash and Cash Equivalents and Restricted Time Deposits (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 24,333	$ 25,116	$ 24,810	$ 26,169
Certificate of deposit	4,918	272
United States [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	18,000	19,200
Foreign [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	6,300	5,900
Restricted Time Deposit [Member]
Cash and Cash Equivalents [Line Items]
Certificate of deposit	$ 4,900	$ 300