Accounting for Derivative Instruments and Hedging Activities (Policies)	6 Months Ended
Jun. 30, 2018
Accounting for Derivative Instruments and Hedging Activities [Abstract]
Derivatives Policy	The Company uses derivative instruments to manage foreign exchange risk on the Sterling Notes, and does not hold or issue derivative instruments for speculative trading purposes.

Disclosure of accounting policy for its derivative instruments and hedging activities.

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