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Defined Contribution Plan	12 Months Ended
Defined Contribution Plan	Dec. 31, 2017
Retirement Benefits [Abstract]
Defined Contribution Plan	DEFINED CONTRIBUTION PLAN We have a retirement savings plan available for all our U.S. employees who have met minimum length-of-service requirements. Our contributions are determined based upon amounts contributed by the employees with additional contributions made at the discretion of the Board of Directors. Costs related to this plan were $285, $376 and $433 in 2017, 2016 and 2015, respectively.