Basis of Presentation - Narrative (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cash payments for income taxes	$ 29.5	$ 54.5
Cash refunds for income taxes	4.6	$ 7.7
Prepaid Expenses and Other Current Assets
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Income taxes receivable	$ 16.3		$ 12.0