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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expense and depreciation and amortization)	$ 15,077	$ 14,121	$ 44,617	$ 40,839
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	10.30%	10.90%	10.20%	10.60%
Total uncompensated care	$ 10,958	$ 9,042	$ 31,571	$ 25,516
Multiply by the cost-to-charges ratio	10.30%	10.90%	10.20%	10.60%
Estimated cost of total uncompensated care	$ 1,138	$ 975	$ 3,220	$ 2,705