Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 14,779	$ 13,157
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	10.10%	10.40%
Total uncompensated care	$ 10,002	$ 7,991
Multiply by the cost-to-charges ratio	10.10%	10.40%
Estimated cost of total uncompensated care	$ 1,010	$ 831