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Summary of Significant Accounting Policies Foreign Currency Adjustments (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Accounting Policies [Abstract] |  |  |
Net foreign translation and transaction activity | $ 88,000 | $ 30,000 | $ 89,000

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