Business Combinations - Estimated Fair Values of Aggregate Assets and Liabilities Acquired (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Fair Value Of Assets And Liabilities Statement [Line Items]
Cash paid	$ 145
Other payable	14
Recorded earn-out payable	28	$ 51
Total consideration	187
Maximum potential earn-out payable	54
Allocation of purchase price:
Cash and equivalents	6
Fiduciary cash	21
Fiduciary receivables	1
Other current assets	7
Goodwill	127
Other assets	2
Total assets acquired	224
Fiduciary liabilities	(22)
Other current liabilities	(2)
Deferred income tax, net	7
Total liabilities assumed	(31)
Acquired non-controlling interest	(6)
Net assets acquired	187
Purchased Customer Accounts and Other
Allocation of purchase price:
Intangible assets	$ 60