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Long-Term Debt - Additional Information (Detail) - USD ($)
12 Months Ended
Mar. 05, 2020
Dec. 05, 2016
Dec. 31, 2020
Dec. 31, 2019
Debt Instrument [Line Items]        
Debt instrument redemption price percentage 100.00%   101.00%  
Maximum consolidated debt reduction for unrestricted cash and cash equivalents for debt covenant calculation     $ 200,000,000.0  
Outstanding letters of credit     32,000,000.0  
Minimum        
Debt Instrument [Line Items]        
Reduction of consolidated debt in the debt ratio calculation     $ 50,000,000.0  
Including Acquisition Bridge Debt | Maximum        
Debt Instrument [Line Items]        
Debt covenant     3.50  
Excluding Acquisition Bridge Debt | Maximum        
Debt Instrument [Line Items]        
Debt covenant     3.75  
Revolving Facility        
Debt Instrument [Line Items]        
Credit facility commitment   $ 700,000,000.0    
Senior unsecured revolving facility, maturity period   5 years    
Debt instrument maturity period     Dec. 05, 2024  
Outstanding letters of credit     $ 2,600,000 $ 2,300,000
Available for borrowing under revolving facility     697,400,000 697,700,000
US Treasury (UST) Interest Rate        
Debt Instrument [Line Items]        
Basis spread on variable rate 0.30%      
2.500% Senior Notes, Due 2030        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt $ 500,000,000   $ 500,000,000.0  
Interest rate on notes 2.50%   2.50%  
Maturity year 2030   2030  
Floating Rate Senior Notes, Due 2020        
Debt Instrument [Line Items]        
Maturity year     2020  
Debt Instrument Payable Upon Maturity $ 300,000,000.0      
4.25% Senior Notes, Due 2024        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 400,000,000.0  
Interest rate on notes     4.25%  
Maturity year     2024  
7% Debentures, Due 2025        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 125,000,000.0  
Interest rate on notes     7.00%  
Maturity year     2025  
3.450% Senior Notes, Due 2027        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 300,000,000.0  
Interest rate on notes     3.45%  
Maturity year     2027  
3.500% Senior Notes, Due 2027        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 500,000,000.0  
Interest rate on notes     3.50%  
Maturity year     2027  
6.25% Senior Notes, Due 2037        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 230,000,000.0  
Interest rate on notes     6.25%  
Maturity year     2037  
4.250% Senior Notes, Due 2047        
Debt Instrument [Line Items]        
Aggregate principal amount of long term debt     $ 600,000,000.0  
Interest rate on notes     4.25%  
Maturity year     2047  
Trade Receivable Facility        
Debt Instrument [Line Items]        
Credit facility commitment     $ 400,000,000.0  
Debt instrument maturity period     Sep. 22, 2021  
Outstanding borrowing under credit facility     $ 0 $ 340,000,000.0
Trade Receivable Facility | Conduit Lenders        
Debt Instrument [Line Items]        
Basis spread on variable rate     0.85%  
Trade Receivable Facility | London Interbank Offered Rate(LIBOR)        
Debt Instrument [Line Items]        
Basis spread on variable rate     1.00%