Restructuring Costs (Restructuring Activities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Restructuring Reserve [Roll Forward]
Liability at beginning of period			$ 130	$ 146	$ 146
Restructuring charges	$ 44	$ 65	86	118	301
Cash payments			(153)		(271)
Non-cash charges			(3)		(46)
Liability at end of period	60		60		130
Severance
Restructuring Reserve [Roll Forward]
Liability at beginning of period			89	88	88
Restructuring charges			42		148
Cash payments			(102)		(147)
Non-cash charges			0		0
Liability at end of period	29		29		89
Real Estate Related Costs
Restructuring Reserve [Roll Forward]
Liability at beginning of period			39	56	56
Restructuring charges			21		96
Cash payments			(26)		(69)
Non-cash charges			(3)		(44)
Liability at end of period	31		31		39
Information Technology
Restructuring Reserve [Roll Forward]
Liability at beginning of period			0	0	0
Restructuring charges			11		15
Cash payments			(11)		(13)
Non-cash charges			0		(2)
Liability at end of period	0		0		0
Consulting and Other Outside Services
Restructuring Reserve [Roll Forward]
Liability at beginning of period			2	$ 2	2
Restructuring charges			12		42
Cash payments			(14)		(42)
Non-cash charges			0		0
Liability at end of period	$ 0		$ 0		$ 2