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Long-Term Debt - Additional Information (Details) - USD ($)
3 Months Ended 9 Months Ended
Jun. 21, 2018
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Mar. 31, 2017
Debt Instrument [Line Items]              
Repayments of commercial paper notes       $ 135,800,000      
Net investment hedge (losses) gains   $ (3,621,000) $ (9,681,000) $ 4,947,000 $ (37,600,000)    
Commercial paper notes              
Debt Instrument [Line Items]              
Weighted average interest rate   2.39%   2.39%      
Debt instrument maturity period       31 days      
1.875% Senior Notes              
Debt Instrument [Line Items]              
Debt instrument, interest rate   1.875%   1.875%   1.875% 1.875%
Revolving Credit Facility              
Debt Instrument [Line Items]              
Revolving credit facility, maximum borrowing capacity $ 1,000,000,000.0            
Interest rate margin       1.125%      
Revolving credit facility, borrowings outstanding   $ 0   $ 0      
Minimum | Revolving Credit Facility              
Debt Instrument [Line Items]              
Interest rate margin 0.91%            
Maximum | Revolving Credit Facility              
Debt Instrument [Line Items]              
Interest rate margin 1.50%