Fair Value Measurements (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Debt	$ 358,293,000	$ 347,878,000
Convertible Debt, Fair Value Disclosures	475,100,000	509,700,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	75,307,000	37,034,000
Foreign Currency Contracts, Liability, Fair Value Disclosure	(63,772,000)	(25,891,000)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	75,307,000	37,034,000
Foreign Currency Contracts, Liability, Fair Value Disclosure	(63,772,000)	(25,891,000)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	$ 0	$ 0