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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 13,523	$ 12,694	$ 12,602	$ 12,517	$ 12,274	$ 11,451	$ 11,529	$ 11,423	$ 51,336	$ 46,677	$ 43,614
Net income	1,273	764	927	1,181	1,245	896	966	1,282	4,145	4,389	2,743
Net income attributable to HCA Healthcare, Inc.	$ 1,071	$ 612	$ 783	$ 1,039	$ 1,064	$ 759	$ 820	$ 1,144	$ 3,505	$ 3,787	$ 2,216
Basic earnings per share	$ 3.16	$ 1.80	$ 2.29	$ 3.03	$ 3.09	$ 2.20	$ 2.35	$ 3.26	$ 10.27	$ 10.90	$ 6.12
Diluted earnings per share	$ 3.09	$ 1.76	$ 2.25	$ 2.97	$ 3.01	$ 2.15	$ 2.31	$ 3.18	$ 10.07	$ 10.66	$ 5.95