Fair Values of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)
Dec. 31, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Convertible note hedge asset $ 25,471,000 $ 0
Convertible Debt Conversion Feature, Fair Value (30,708,000) 0
Convertible Debt Bond Hedge [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Convertible note hedge asset 25,471,000  
Foreign exchange forward | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 971,000 2,129,000
Foreign exchange forward | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets / (Liabilities) - Level I    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 0 0
Foreign exchange forward | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 971,000 2,129,000
Foreign exchange forward | Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs - Level III    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 0 $ 0
Convertible Debt Conversion Feature [Member] | Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Convertible Debt Conversion Feature, Fair Value (30,708,000)  
Convertible Debt Bond Hedge [Member] | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 25,471,000  
Convertible Debt Bond Hedge [Member] | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets / (Liabilities) - Level I    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 0  
Convertible Debt Bond Hedge [Member] | Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs - Level III    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 0  
Convertible Debt Conversion Feature [Member] | Fair Value, Measurements, Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net (30,708,000)  
Convertible Debt Conversion Feature [Member] | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets / (Liabilities) - Level I    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net 0  
Convertible Debt Conversion Feature [Member] | Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs - Level III    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivative assets (liabilities), at fair value, net $ 0