Earnings Per Share - Schedule of Computations of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income attributable to HCA Healthcare, Inc.	$ 6,956	$ 3,754	$ 3,505
Weighted average common shares outstanding	323,315	338,274	341,210
Effect of dilutive incremental shares	5,437	5,331	7,016
Shares used for diluted earnings per share	328,752	343,605	348,226
Basic earnings per share	$ 21.52	$ 11.10	$ 10.27
Diluted earnings per share	$ 21.16	$ 10.93	$ 10.07