Restructuring Costs (Restructuring Activities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Restructuring Reserve [Roll Forward]
Liability at beginning of period			$ 117	$ 130	$ 130
Restructuring charges	$ 46	$ 54	96	140	276
Cash payments			(138)		(270)
Non-cash charges			(2)		(19)
Liability at end of period	73		73		117
Severance
Restructuring Reserve [Roll Forward]
Liability at beginning of period			75	89	89
Restructuring charges			70		163
Cash payments			(101)		(177)
Non-cash charges			0		0
Liability at end of period	44		44		75
Real Estate Related Costs
Restructuring Reserve [Roll Forward]
Liability at beginning of period			42	39	39
Restructuring charges			19		66
Cash payments			(30)		(45)
Non-cash charges			(2)		(18)
Liability at end of period	29		29		42
Information Technology
Restructuring Reserve [Roll Forward]
Liability at beginning of period			0	0	0
Restructuring charges			0		25
Cash payments			0		(24)
Non-cash charges			0		(1)
Liability at end of period	0		0		0
Consulting and Other Outside Services
Restructuring Reserve [Roll Forward]
Liability at beginning of period			0	$ 2	2
Restructuring charges			7		22
Cash payments			(7)		(24)
Non-cash charges			0		0
Liability at end of period	$ 0		$ 0		$ 0