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Leases - Additional Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Leases [Abstract]      
Total opearting lease costs $ 44.2 $ 53.5  
Variable lease costs 6.6 $ 8.5  
Total operating lease expense     $ 48.7
Operating lease agreements, additional area leased 1.8    
Operating lease right-of-use assets 41.8    
Lease liabilities 42.6    
Lease Termination Fee 18.0    
Additional lease gain $ 0.8