Acquisitions, Dispositions And Impairments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended				9 Months Ended			9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 Healthone [Member]	Sep. 30, 2011 Hospitals [Member]	Sep. 30, 2011 Hospitals [Member] National Group [Member] Other Acquisition [Member]	Sep. 30, 2011 Other Healthcare Entity [Member]	Sep. 30, 2012 Other Healthcare Entity [Member] Other Acquisition [Member]	Sep. 30, 2011 Other Healthcare Entity [Member] Other Acquisition [Member]	Sep. 30, 2012 Real Estate [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	$ 58			$ 136		$ 109	$ 73
Liability assumed on acquisition	33
Goodwill recorded on acquisition	53
Increase in noncontrolling interests on business acquisition	30	30
Decrease in property and equipment on business acquisition		26
Increase in goodwill on business acquisition		56
Proceeds from sales of business			55					17
Pretax gain on sales of business					$ 3			$ 4