Basis of Presentation and Significant Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 12,524	$ 11,950	$ 25,268	$ 23,593
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	11.00%	11.10%	11.20%	11.20%
Total uncompensated care	$ 8,457	$ 7,696	$ 15,462	$ 14,517
Multiply by the cost-to-charges ratio	11.00%	11.10%	11.20%	11.20%
Estimated cost of total uncompensated care	$ 940	$ 848	$ 1,732	$ 1,626