Business Acquisitions (Acquired tangible assets and liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Business Combination and Asset Acquisition [Abstract]
Cash, cash equivalents and short-term investments	$ 170	$ 808
Accounts receivable and other current assets	240	295
Property, equipment and other long-term assets	109	102
Medical claims and other policyholder liabilities payable	(185)	(571)
Accounts payable and other current liabilities	(20)	(179)
Other long-term liabilities	(15)	(6)
Deferred tax liabilities	(32)	(556)
Total net tangible assets	$ 267	$ (107)