Business Acquisitions and Divestitures - Acquired Tangible Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Cash, cash equivalents and short-term investments	$ 498	$ 484
Accounts receivable and other current assets	93	847
Property, equipment and other long-term assets	6	309
Medical claims and other policyholder liabilities payable	(404)	(154)
Accounts payable and other current liabilities	(19)	(1,005)
Other long-term liabilities	(2)	(242)
Business Combination, Recognized Asset Acquired, Deferred Tax Asset	21
Deferred tax assets (liabilities)		(475)
Total net tangible assets (liabilities)	$ 193	$ (236)