Consolidated Income Statements - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues before provision for doubtful accounts									$ 47,653	$ 44,747	$ 43,591
Provision for doubtful accounts									4,039	3,257	3,913
Revenues	$ 11,562	$ 10,696	$ 10,733	$ 10,623	$ 10,641	$ 10,270	$ 10,319	$ 10,260	43,614	41,490	39,678
Salaries and benefits									20,059	18,897	18,115
Supplies									7,316	6,933	6,638
Other operating expenses									8,051	7,496	7,056
Equity in earnings of affiliates									(45)	(54)	(46)
Depreciation and amortization									2,131	1,966	1,904
Interest expense									1,690	1,707	1,665
Losses (gains) on sales of facilities	1	4	1	1	15	2	4	2	(8)	(23)	5
Losses on retirement of debt		25				2			39	4	135
Legal claim costs (benefits)										(246)	249
Total expenses including equity in earnings of affiliates									39,233	36,680	35,721
Income before income taxes									4,381	4,810	3,957
Provision for income taxes									1,638	1,378	1,261
Net income	641	530	795	777	1,085	745	791	811	2,743	3,432	2,696
Net income attributable to noncontrolling interests									527	542	567
Net income attributable to HCA Healthcare, Inc.	$ 474	$ 426	$ 657	$ 659	$ 920	$ 618	$ 658	$ 694	$ 2,216	$ 2,890	$ 2,129
Per share data:
Basic earnings per share	$ 1.34	$ 1.18	$ 1.79	$ 1.78	$ 2.46	$ 1.63	$ 1.70	$ 1.75	$ 6.12	$ 7.53	$ 5.14
Diluted earnings per share	$ 1.30	$ 1.15	$ 1.75	$ 1.74	$ 2.39	$ 1.59	$ 1.65	$ 1.69	$ 5.95	$ 7.30	$ 4.99
Shares used in earnings per share calculations (in millions):
Basic									362,305	383,591	414,193
Diluted									372,221	395,851	426,721