Fair Value Measurements - Fair Value Liabilities Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - Fair Value Measurements at Reporting Date Using: Significant Unobservable Inputs (Level 3) [Member] $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance December 31, 2019	$ 28.8
New contingent payments related to the 2020 acquisitions	31.3
Changes in estimates	2.8
Settlements	(15.0)
Foreign currency impact	0.3
Ending balance December 31, 2020	$ 48.2