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Debt - Additional Information (Detail)
1 Months Ended 9 Months Ended
Apr. 25, 2018
USD ($)
May 31, 2019
USD ($)
Sep. 30, 2020
USD ($)
Dec. 31, 2019
USD ($)
Debt Instrument [Line Items]        
Leverage ratio covenant period     12 months  
Debt     $ 805,200,000 $ 1,029,100,000
Repayments of principal in next twelve months     103,800,000  
Line of Credit | Term Loans Due 2023        
Debt Instrument [Line Items]        
Long-term Debt, Gross       200,000,000.0
Optional line of credit limit increase       300,000,000.0
Line of Credit | Revolving Credit Facility        
Debt Instrument [Line Items]        
Credit facility maximum borrowing capacity $ 800,000,000.0 $ 900,000,000.0    
Debt term 5 years      
Increase in line of credit   $ 100,000,000.0    
Line of Credit Facility, Remaining Borrowing Capacity     897,800,000  
Debt     2,200,000 35,800,000
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     3.75  
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     1.00  
EBITDA ratio for debt     1.00  
Commercial Paper        
Debt Instrument [Line Items]        
Commercial paper     $ 0 $ 117,800,000
Other Credit Facilities [Member]        
Debt Instrument [Line Items]        
Credit facility maximum borrowing capacity     21,100,000  
Borrowings outstanding     $ 0