XML 81 R66.htm IDEA: XBRL DOCUMENT v3.8.0.1
Fair Value Measurement (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Foreign currency forward contracts outstanding $ 0 $ 0
Convertible Senior Notes due 2022 | Significant Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of convertible senior notes issued $ 52,600,000