Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 15,466	$ 14,779
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	9.60%	10.10%
Total uncompensated care	$ 10,993	$ 10,002
Multiply by the cost-to-charges ratio	9.60%	10.10%
Estimated cost of total uncompensated care	$ 1,055	$ 1,010

$ 15,466

$ 14,779

$ 10,993

$ 10,002

$ 1,055

$ 1,010