Acquisitions and Dispositions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Proceeds from sale of business	$ 38	$ 31
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	20
Proceeds from sale of business	38
Hospitals [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	14	146
Hospitals [Member] | Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business		13
Proceeds from sale of business		31
Other Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	83
Outsource Group [Member]
Business Acquisition [Line Items]
Cash paid for acquisition		317
Business acquisition, Goodwill		176
Business acquisition, Identifiable intangible assets		$ 125