Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts [Abstract]
Accounts Receivable, Allowance for Credit Loss	$ 25.3	$ 18.8	$ 19.0	$ 13.5
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	11.4	7.9
Accounts Receivable, Allowance for Credit Loss, Writeoff	(5.1)	$ (2.6)
Goodwill, Foreign Currency Translation Gain (Loss)	68.1
Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss)	$ 39.8