Goodwill and Other Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2026	Dec. 31, 2025
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 804	$ 748
Additions from business combinations	0	56
Goodwill, Ending Balance	804	804
Segment Reporting, Reconciling Item, Corporate Nonsegment
Goodwill [Roll Forward]
Goodwill, Beginning Balance	102	102
Additions from business combinations	0	0
Goodwill, Ending Balance	102	102
Wealth Solutions Segment \| Segment Reporting, Reconciling Item, Corporate Nonsegment
Goodwill [Roll Forward]
Goodwill, Ending Balance	72
Health Solutions Segment \| Segment Reporting, Reconciling Item, Corporate Nonsegment
Goodwill [Roll Forward]
Goodwill, Ending Balance	20
Investment Management Segment \| Segment Reporting, Reconciling Item, Corporate Nonsegment
Goodwill [Roll Forward]
Goodwill, Ending Balance	10
Wealth Solutions Segment \| Operating Segments
Goodwill [Roll Forward]
Goodwill, Beginning Balance	73	17
Additions from business combinations	0	56
Goodwill, Ending Balance	73	73
Health Solutions Segment \| Operating Segments
Goodwill [Roll Forward]
Goodwill, Beginning Balance	343	343
Additions from business combinations	0	0
Goodwill, Ending Balance	343	343
Investment Management Segment \| Operating Segments
Goodwill [Roll Forward]
Goodwill, Beginning Balance	286	286
Additions from business combinations	0	0
Goodwill, Ending Balance	$ 286	$ 286

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant