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Summary of Significant Accounting Policies (Foreign Currency Exchange) (Details) $ in Millions | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014
--- | --- | --- | ---
Significant Transactions |  |  |
Net unrealized foreign currency translation losses | $ (1.4) | $ (145.6) |
Israel, New Shekels |  |  |
Significant Transactions |  |  |
Foreign currency exchange rate | 3.8476 | 3.9051 | 3.8865
SEK |  |  |
Significant Transactions |  |  |
Foreign currency exchange rate |  | 8.4247 | 7.7737
GBP |  |  |
Significant Transactions |  |  |
Foreign currency exchange rate | 0.8074 | 0.6757 | 0.6426
Euro Member Countries, Euro |  |  |
Significant Transactions |  |  |
Foreign currency exchange rate | 0.9479 | 0.9189 | 0.8245

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