MEDICARE PART D (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Other current assets	$ 5,913	$ 5,276
Trade accounts payable and accrued expenses	(4,957)	(4,013)
Other long-term assets	4,563	2,128
Other long-term liabilities	(2,545)	(1,787)
Risk Corridor Settlement
Segment Reporting Information [Line Items]
Other current assets	170	216
Trade accounts payable and accrued expenses	(14)	(39)
Net current asset	156	177
Other long-term assets	244	8
Other long-term liabilities	(257)	(90)
Net long-term liability	(13)	(82)
Total net asset	143	95
CMS Subsidies/ Discounts
Segment Reporting Information [Line Items]
Other current assets	1,681	1,420
Trade accounts payable and accrued expenses	(1,139)	(253)
Net current asset	542	1,167
Other long-term assets	0	0
Other long-term liabilities	0	0
Net long-term liability	0	0
Total net asset	$ 542	$ 1,167