Dispositions and Acquisitions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Significant Acquisitions and Disposals [Line Items]
Payment to acquired real properties	$ 1	$ 25
Aggregate cash proceeds from divestiture of businesses	$ 37	$ 56
Peak Behavioral Health Services
Significant Acquisitions and Disposals [Line Items]
Number of acute care hospital beds included in sale	104
Previously Closed [Member]
Significant Acquisitions and Disposals [Line Items]
Real property previously closed and sold	5	2
Hospital San Juan Capestrano
Significant Acquisitions and Disposals [Line Items]
Number of acute care hospital beds included in sale		108