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Long-Term Debt and Financing Arrangements - Additional Information (Detail) - USD ($)
$ in Millions
Jul. 01, 2017
Jun. 30, 2021
Dec. 31, 2020
Standby Letters of Credit [Member]      
Line Of Credit Facility [Line Items]      
Outstanding letters of credit   $ 37.4  
Revolving Credit Facility [Member] | Bank Revolving Line Of Credit [Member]      
Line Of Credit Facility [Line Items]      
Unused and available borrowings under bank revolving line of credit and credit agreement   $ 312.6 $ 312.3
Credit Agreement [Member]      
Line Of Credit Facility [Line Items]      
Amount of credit agreement $ 350.0    
Line of Credit Facility, Expiration Date Jul. 01, 2022