Quarterly Consolidated Financial Information - Schedule of Quarterly Consolidated Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 12,274	$ 11,451	$ 11,529	$ 11,423	$ 11,562	$ 10,696	$ 10,733	$ 10,623	$ 46,677	$ 43,614	$ 41,490
Net income	1,245	896	966	1,282	641	530	795	777	4,389	2,743	3,432
Net income attributable to HCA Healthcare, Inc.	$ 1,064	$ 759	$ 820	$ 1,144	$ 474	$ 426	$ 657	$ 659	$ 3,787	$ 2,216	$ 2,890
Basic earnings per share	$ 3.09	$ 2.20	$ 2.35	$ 3.26	$ 1.34	$ 1.18	$ 1.79	$ 1.78	$ 10.90	$ 6.12	$ 7.53
Diluted earnings per share	$ 3.01	$ 2.15	$ 2.31	$ 3.18	$ 1.30	$ 1.15	$ 1.75	$ 1.74	$ 10.66	$ 5.95	$ 7.30