Leases - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Leases [Line Items]
Leases commenced during the period	$ 69.9
Weighted average discount rate	3.20%	3.80%
Weighted average remaining lease term	13 years 6 months	4 years 10 months 24 days
Operating cash flows used for operating leases	$ 5.1	$ 5.7
Remaining 2020 lease payment	3.7
Tenant improvement allowance	13.7
Undiscounted lease liability amount	$ 24.6
Year of lease commencement	2020
Minimum [Member]
Leases [Line Items]
Expected lease term	21 years