Earnings Per Share (Schedule Of Computation Of Basic And Diluted Earnings Per Share) (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share [Line Items]
Net income attributable to HCA Holdings, Inc.	$ 360	$ 61	$ 1,291	$ 530
Weighted average common shares outstanding	440,899	508,417	439,441	489,924
Effect of dilutive securities	18,616	19,098	19,381	19,659
Shares used for diluted earnings per share	459,515	527,515	458,822	509,583
Earnings per share:
Basic earnings per share	$ 0.82	$ 0.12	$ 2.94	$ 1.08
Diluted earnings per share	$ 0.78	$ 0.11	$ 2.81	$ 1.04