Business Combinations - Estimated Fair Values of Aggregate Assets and Liabilities Acquired (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Fair Value Of Assets And Liabilities Statement [Line Items]
Cash paid	$ 121
Other payable	7
Recorded earn-out payable	19	$ 40
Total consideration	147
Maximum potential earn-out payable	38
Allocation of purchase price:
Cash and equivalents	2
Fiduciary cash	21
Other current assets	7
Goodwill	108
Total assets acquired	175
Fiduciary liabilities	(21)
Other current liabilities	(1)
Total liabilities assumed	(22)
Acquired non-controlling interest	(6)
Net assets acquired	147
Purchased Customer Accounts and Other
Allocation of purchase price:
Intangible assets	$ 37