Acquisitions and Dispositions (Allocation of Acquisition Costs) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Cash	$ 662	$ 332
Estimated fair value of deferred/contingent purchase consideration	54	8
Total consideration	716	340
Allocation of purchase price:
Goodwill	17,516	$ 16,621	$ 17,231	$ 16,251
Current Fiscal Period Acquisitions
Business Acquisition [Line Items]
Cash	662
Estimated fair value of deferred/contingent purchase consideration	54
Total consideration	716
Allocation of purchase price:
Cash and cash equivalents	13
Cash and cash equivalents held in a fiduciary capacity	5
Net receivables	49
Other current assets	22
Goodwill	430
Other intangible assets	215
Fixed assets, net	3
Other assets	2
Total assets acquired	739
Current liabilities	9
Fiduciary liabilities	5
Other liabilities	9
Total liabilities assumed	23
Net assets acquired	$ 716