Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful patient accounts	$ 3,729	$ 3,773
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	114,690,205	113,876,580
Common stock, shares outstanding	114,690,205	113,876,580