Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful patient accounts	$ 3,825	$ 3,504
Other current assets of hospitals held for sale	5	38
Noncurrent assets of hospitals held for sale	32	90
Current liabilities of hospitals held for sale	$ 1	$ 10
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	119,158,604	117,701,087
Common stock, shares outstanding	118,183,055	116,725,538
Treasury stock, shares	975,549	975,549