Acquisitions - Summary of Allocation of Purchase Price for Acquisitions of Acquiree (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Oct. 01, 2023	Dec. 31, 2022	Aug. 23, 2022	Mar. 25, 2022	Mar. 16, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill	$ 8,969.5		$ 8,863.0				$ 8,045.5
Blue Prism
Business Acquisition [Line Items]
Accounts receivable						$ 50.1
Property, plant and equipment						1.8
Other assets						11.2
Operating lease right-of-use assets						4.4
Goodwill						950.6
Accounts payable						(6.6)
Accrued employee compensation and other liabilities						(64.0)
Deferred revenue						(166.9)
Deferred income taxes						(111.1)
Consideration paid, net of cash acquired						1,477.5
Iress Managed Funds Administration Business
Business Acquisition [Line Items]
Accounts receivable		$ 2.4
Property, plant and equipment		0.0
Other assets		0.7
Operating lease right-of-use assets		0.0
Goodwill		20.4
Accounts payable		0.0
Accrued employee compensation and other liabilities		1.3
Deferred revenue		0.0
Deferred income taxes		(3.9)
Consideration paid, net of cash acquired		32.9
Hubwise
Business Acquisition [Line Items]
Accounts receivable					$ 0.7
Property, plant and equipment					0.1
Other assets					0.3
Operating lease right-of-use assets					0.0
Goodwill					50.0
Accounts payable					(0.2)
Accrued employee compensation and other liabilities					(0.7)
Deferred revenue					0.0
Deferred income taxes					(7.4)
Consideration paid, net of cash acquired					75.5
Tier1
Business Acquisition [Line Items]
Accounts receivable				$ 0.3
Property, plant and equipment				0.1
Other assets				0.2
Operating lease right-of-use assets				0.0
Goodwill				21.6
Accounts payable				(1.0)
Accrued employee compensation and other liabilities				(2.0)
Deferred revenue				(8.6)
Deferred income taxes				0.0
Consideration paid, net of cash acquired				33.3
Acquired Client Relationships and Contracts [Member] | Blue Prism
Business Acquisition [Line Items]
Intangible assets acquired						520.0
Acquired Client Relationships and Contracts [Member] | Iress Managed Funds Administration Business
Business Acquisition [Line Items]
Intangible assets acquired		13.9
Acquired Client Relationships and Contracts [Member] | Hubwise
Business Acquisition [Line Items]
Intangible assets acquired					23.0
Acquired Client Relationships and Contracts [Member] | Tier1
Business Acquisition [Line Items]
Intangible assets acquired				16.3
Completed Technology [Member] | Blue Prism
Business Acquisition [Line Items]
Intangible assets acquired						250.0
Completed Technology [Member] | Iress Managed Funds Administration Business
Business Acquisition [Line Items]
Intangible assets acquired		0.0
Completed Technology [Member] | Hubwise
Business Acquisition [Line Items]
Intangible assets acquired					8.7
Completed Technology [Member] | Tier1
Business Acquisition [Line Items]
Intangible assets acquired				6.4
Trade Names [Member] | Blue Prism
Business Acquisition [Line Items]
Intangible assets acquired						$ 38.0
Trade Names [Member] | Iress Managed Funds Administration Business
Business Acquisition [Line Items]
Intangible assets acquired		$ 0.7
Trade Names [Member] | Hubwise
Business Acquisition [Line Items]
Intangible assets acquired					$ 1.0
Trade Names [Member] | Tier1
Business Acquisition [Line Items]
Intangible assets acquired				$ 0.0