Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful patient accounts	$ 3,732	$ 4,110
Other current assets of hospitals held for sale	5	17
Noncurrent assets of hospitals held for sale	26	41
Current liabilities of hospitals held for sale	$ 3	$ 6
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	113,643,956	113,732,933
Common stock, shares outstanding	113,643,956	112,757,384
Treasury stock, shares	0	975,549