Leases - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Leases [Line Items]
Lessee, operating leases, option to extend	Leases with renewal options allow the Company to extend the lease term typically between 1 to 10 years.
Lessee, operating lease, existence of option to extend [true false]	true
Lessee, operating lease, option to terminate	real estate lease agreements include Company options to either extend and/or terminate the lease
Lessee, operating lease, existence of option to terminate [true false]	true
Leases commenced during the period	$ 127.2
Weighted average discount rate	3.00%	3.80%
Weighted average remaining lease term	15 years	5 years
Operating cash flows used for operating leases	$ 15.4	$ 17.4
Remaining 2020 lease payment	0.3
2021 lease payment	12.1
Tenant improvement allowance	5.2
Tenant improvement allowance for 2021	$ 10.0
Minimum [Member]
Leases [Line Items]
Operating leases, options to extend leases term	1 year
Maximum [Member]
Leases [Line Items]
Operating leases, options to extend leases term	10 years