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Debt - Additional Information (Detail) - USD ($)
1 Months Ended 9 Months Ended
Apr. 25, 2018
May 31, 2019
Sep. 30, 2019
Dec. 31, 2018
Debt Instrument [Line Items]        
Leverage ratio covenant period     12 months  
Debt     $ 1,118,700,000 $ 787,600,000
Aggregate principal amount maturing in the next twelve months     324,000,000.0  
Line of Credit | Revolving Credit Facility        
Debt Instrument [Line Items]        
Debt term 5 years      
Credit facility maximum borrowing capacity $ 800,000,000.0 $ 900,000,000.0    
Credit facility available borrowing capacity     706,700,000  
Optional line of credit limit increase     1,100,000,000.0  
Line of Credit Facility, Increase   $ 100,000,000.0    
Debt     $ 3,600,000 26,200,000
Average interest rate as of September 30, 2019     3.116%  
Line of Credit | Revolving Credit Facility | Maximum        
Debt Instrument [Line Items]        
Debt covenant, unrestricted cash     $ 250,000,000.0  
Debt agreement financial covenant, leverage ratio     1.00  
EBITDA ratio for debt     3.00  
Line of Credit | Revolving Credit Facility | Minimum        
Debt Instrument [Line Items]        
Debt covenant, unrestricted cash     $ 5,000,000.0  
Debt agreement financial covenant, leverage ratio     3.75  
EBITDA ratio for debt     1.00  
Commercial Paper        
Debt Instrument [Line Items]        
Commercial paper     $ 189,700,000 76,000,000.0
Average interest rate as of September 30, 2019     2.575%  
Senior Notes | Senior Notes 4.500% Due 2029        
Debt Instrument [Line Items]        
Debt     $ 400,000,000.0 $ 0
Average interest rate as of September 30, 2019     4.50%  
Other Credit Facilities [Member]        
Debt Instrument [Line Items]        
Credit facility maximum borrowing capacity     $ 20,900,000  
Borrowings outstanding     $ 0