Acquisitions - Summary of Aggregate Final Estimates of Fair Value of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 9,212.0	$ 9,261.8
2020 Acquisitions [Member]
Business Acquisition [Line Items]
Current assets	31.7
Goodwill	185.5
Other assets	5.4
Total assets acquired	469.6
Current liabilities	4.8
Deferred income taxes	43.5
Other long-term liabilities	0.1
Total liabilities assumed	48.4
Net assets acquired	421.2
Technology [Member] | 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization:	147.9
Trademarks and trade names [Member] | 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization:	1.5
Customer relationships [Member] | 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization:	92.7
Other [Member] | 2020 Acquisitions [Member]
Business Acquisition [Line Items]
Intangible assets subject to amortization:	$ 4.9