Supplemental Disclosures (Schedule of Supplemental Cash Flow Disclosures) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Supplemental Cash Flow Information [Abstract]
Assets acquired, excluding cash				$ 1,697	$ 929	$ 8,655
Fiduciary liabilities assumed				(18)	(21)	(1,276)
Liabilities assumed				(213)	(78)	(2,804)
Non-controlling interests assumed				(64)	0	(280)
Fair value of previously-held equity method investment				(390)	0	0
Contingent and deferred purchase consideration				(153)	(183)	(66)
Net cash outflow for acquisitions	$ 0	$ 350	$ 384	859	647	4,229
Interest paid				441	481	427
Income taxes paid, net of refunds				$ 1,069	$ 673	$ 661