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Debt - Credit Facility - Additional Information (Detail) - USD ($)
Feb. 01, 2017
Dec. 31, 2020
Dec. 31, 2019
Debt Instrument [Line Items]      
Aggregate committed amount of credit facility $ 500,000,000    
Minimum [Member]      
Debt Instrument [Line Items]      
Commitment fee 0.125%    
Maximum [Member]      
Debt Instrument [Line Items]      
Commitment fee 0.30%    
Unsecured Revolving Credit Facility [Member]      
Debt Instrument [Line Items]      
Amount of senior unsecured debt $ 1,300,000,000    
Debt instrument, maturity month and year 2021-02    
Aggregate committed amount of credit facility   $ 1,100,000,000 $ 1,300,000,000
Credit facilities, amount outstanding   $ 165,400,000 $ 0
Credit facilities, weighted average interest rate   1.40% 2.00%
Term Loans [Member]      
Debt Instrument [Line Items]      
Amount of senior unsecured debt $ 200,000,000    
Debt instrument maturity date Feb. 01, 2022    
Interest rate at end of period   1.65% 3.30%
Alternate Base Rate [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Applicable margin 0.00%    
Applicable margin for revolving loans 0.00%    
Alternate Base Rate [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Applicable margin 0.95%    
Applicable margin for revolving loans 0.65%    
Eurodollar Loans [Member] | Minimum [Member]      
Debt Instrument [Line Items]      
Applicable margin 0.90%    
Applicable margin for revolving loans 0.875%    
Eurodollar Loans [Member] | Maximum [Member]      
Debt Instrument [Line Items]      
Applicable margin 1.95%    
Applicable margin for revolving loans 1.65%