Summary of Significant Accounting Policies and Basis of Presentation - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 18,823	$ 15,723	$ 15,122	$ 25,735
Short-term investments	1,900	2,200
Banks outside of the United States, primarily in Brazil and Canada
Cash and Cash Equivalents [Line Items]
Short-term investments	1,900	$ 2,200
United States
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	5,000
Canada
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	1,800
Other
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 12,000