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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 12,828	$ 12,803	$ 38,096	$ 36,396
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	11.20%	11.80%	11.20%	11.40%
Total uncompensated care	$ 8,050	$ 7,782	$ 23,512	$ 22,299
Multiply by the cost-to-charges ratio	11.20%	11.80%	11.20%	11.40%
Estimated cost of total uncompensated care	$ 901	$ 916	$ 2,633	$ 2,542