Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 12,744	$ 11,643
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	11.30%	11.40%
Total uncompensated care	$ 7,005	$ 6,821
Multiply by the cost-to-charges ratio	11.30%	11.40%
Estimated cost of total uncompensated care	$ 792	$ 778