Goodwill and Other Intangible Assets (Additional Information) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 17.8	$ 16.5	$ 14.8
Estimated future amortization expense for 2020	14.6
Estimated future amortization expense for 2020	13.8
Estimated future amortization expense for 2021	13.3
Estimated future amortization expense for 2022	12.7
Estimated future amortization expense for 2023 and 2024	$ 11.4