Accounting Policies - Schedule of Estimated Cost of Uncompensated Care (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Gross patient charges	$ 165,614	$ 141,516	$ 125,640
Patient care costs (salaries and benefits, supplies, other operating expenses and depreciation and amortization)	28,533	25,554	23,870
Cost-to-charges ratio	17.20%	18.10%	19.00%
Total uncompensated care	13,841	11,214	9,626
Multiply by the cost-to-charges ratio	17.20%	18.10%	19.00%
Estimated cost of total uncompensated care	$ 2,381	$ 2,030	$ 1,829