Acquisitions and Dispositions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition [Line Items]
Proceeds from sale of business	$ 32	$ 31
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	32
Proceeds from sale of business	32
Hospitals [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	14
Hospitals [Member] | Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business		(12)
Proceeds from sale of business		31
Other Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	$ 13	$ 23