Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expense and depreciation and amortization)	$ 14,121	$ 12,828	$ 40,839	$ 38,096
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	10.90%	11.20%	10.60%	11.20%
Total uncompensated care	$ 9,042	$ 8,050	$ 25,516	$ 23,512
Multiply by the cost-to-charges ratio	10.90%	11.20%	10.60%	11.20%
Estimated cost of total uncompensated care	$ 975	$ 901	$ 2,705	$ 2,633