Acquisitions - Summary of Allocation of Purchase Price for Acquisitions of Acquiree (Detail) - Capita Life Pensions Services Limited [Member] $ in Millions	Mar. 31, 2021 USD ($)
Business Acquisition [Line Items]
Accounts receivable	$ 3.8
Fixed assets	0.5
Other assets	5.5
Accounts payable	(3.8)
Deferred revenue	(3.1)
Other liabilities assumed	(7.1)
Gain on bargain purchase	(2.9)
Consideration paid, net of cash acquired	$ (7.1)