Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Goodwill [Line Items]
Amortization expense associated with identifiable intangible assets	$ 2.0	$ 0.3
Estimated total amortization expense 2020	3.2
Estimated total amortization expense 2021	5.7
Estimated total amortization expense 2022	6.9
Estimated total amortization expense 2023	7.9
Estimated total amortization expense 2024	6.7
Indefinite-lived Intangible Assets [Member]
Goodwill [Line Items]
Goodwill and intangible assets with indefinite lives	$ 147.4		$ 146.9