Earnings Per Share - Schedule of Computations of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net income attributable to HCA Healthcare, Inc.	$ 1,273	$ 1,423
Weighted average common shares outstanding	302,446	338,123
Effect of dilutive incremental shares	4,928	5,198
Shares used for diluted earnings per share	307,374	343,321
Basic earnings per share	$ 4.21	$ 4.21
Diluted earnings per share	$ 4.14	$ 4.14