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Financial Instruments and Risk Management - Narrative (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2017
USD ($)
derivative_instrument
Sep. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Derivative [Line Items]      
Unrecognized pre-tax loss $ 700,000 $ (1,300,000)  
Unrealized pre-tax gain 4,200,000 5,800,000  
Portion or pre-tax gain included in AOCI expected to be included in earnings 4,100,000    
Line of Credit | Senior Secured Term Loan B Facility, net of discount, due 2022      
Derivative [Line Items]      
Face amount of debt 400,000,000.0    
Estimate of Fair Value      
Derivative [Line Items]      
Fair market value of fixed rate long-term debt 0 $ 0  
Reported Value Measurement      
Derivative [Line Items]      
Fair market value of fixed rate long-term debt 600,000,000    
Senior Secured Term Loan B Facility, Due 2022 | Senior Secured Term Loan B Facility, net of discount, due 2022      
Derivative [Line Items]      
Face amount of debt $ 400,000,000.0    
Senior Secured Term Loan B Facility, Due 2022 | Senior Secured Term Loan B Facility, net of discount, due 2022 | Interest Rate Swap      
Derivative [Line Items]      
Variable rate debt hedged     $ 200,000,000
Fixed interest rate     2.034%
Designated as Hedging Instrument | Cash Flow Hedging | Foreign Exchange Forward      
Derivative [Line Items]      
Number of open contracts | derivative_instrument 64,000,000    
Notional value $ 134,300,000.0    
Not Designated as Hedging Instrument | Foreign Exchange Forward      
Derivative [Line Items]      
Number of open contracts | derivative_instrument 10,000,000    
Notional value $ 85,100,000.0