Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expense and depreciation and amortization)	$ 13,561	$ 12,524	$ 26,718	$ 25,268
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	10.50%	11.00%	10.50%	11.20%
Total uncompensated care	$ 8,483	$ 8,457	$ 16,474	$ 15,462
Multiply by the cost-to-charges ratio	10.50%	11.00%	10.50%	11.20%
Estimated cost of total uncompensated care	$ 899	$ 940	$ 1,730	$ 1,732