Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	$ 35,304	$ 33,760	$ 31,478
Cost-to-charges ratio (patient care costs as percentage of gross patient charges)	13.50%	14.50%	15.50%
Total uncompensated care	$ 20,455	$ 18,287	$ 15,943
Multiply by the cost-to-charges ratio	13.50%	14.50%	15.50%
Estimated cost of total uncompensated care	$ 2,761	$ 2,652	$ 2,471