Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Schedule of Condensed Consolidating Comprehensive Income Statement (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Statement of Income Captions [Line Items]
Revenues	$ 11,451	$ 10,696	$ 34,403	$ 32,052
Salaries and benefits	5,377	5,081	15,940	14,878
Supplies	1,890	1,777	5,722	5,369
Other operating expenses	2,097	2,075	6,325	5,970
Equity in earnings of affiliates	(9)	(13)	(25)	(36)
Depreciation and amortization	582	539	1,697	1,581
Interest expense (income)	442	427	1,309	1,257
Losses (gains) on sales of facilities	(6)	(7)	(420)	(10)
Losses on retirement of debt	9	39	9	39
Total expenses including equity in earnings of affiliates	10,382	9,918	30,557	29,048
Income (loss) before income taxes	1,069	778	3,846	3,004
Provision (benefit) for income taxes	173	248	702	902
Net income (loss)	896	530	3,144	2,102
Net income attributable to noncontrolling interests	137	104	421	360
Net income (loss) attributable to HCA Healthcare, Inc.	759	426	2,723	1,742
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	754	451	2,735	1,812
Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	11,451	10,696	34,403	32,052
HCA Healthcare, Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Other operating expenses	2		7	5
Equity in earnings of affiliates	(728)	(436)	(2,670)	(1,702)
Interest expense (income)	16	16	48	48
Total expenses including equity in earnings of affiliates	(710)	(420)	(2,615)	(1,649)
Income (loss) before income taxes	710	420	2,615	1,649
Provision (benefit) for income taxes	(49)	(6)	(108)	(93)
Net income (loss)	759	426	2,723	1,742
Net income (loss) attributable to HCA Healthcare, Inc.	759	426	2,723	1,742
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	754	451	2,735	1,812
HCA Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Interest expense (income)	913	792	2,617	2,280
Losses on retirement of debt	9	39	9	39
Total expenses including equity in earnings of affiliates	922	831	2,626	2,319
Income (loss) before income taxes	(922)	(831)	(2,626)	(2,319)
Provision (benefit) for income taxes	(214)	(307)	(610)	(856)
Net income (loss)	(708)	(524)	(2,016)	(1,463)
Net income (loss) attributable to HCA Healthcare, Inc.	(708)	(524)	(2,016)	(1,463)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	(703)	(522)	(1,974)	(1,458)
Subsidiary Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Salaries and benefits	3,090	2,915	9,184	8,689
Supplies	1,115	1,033	3,383	3,163
Other operating expenses	1,137	1,093	3,387	3,207
Equity in earnings of affiliates	(2)	(1)	(5)	(4)
Depreciation and amortization	340	311	992	923
Interest expense (income)	(423)	(342)	(1,179)	(947)
Losses (gains) on sales of facilities	(6)	(3)	(378)	(6)
Management fees	(158)	(159)	(473)	(479)
Total expenses including equity in earnings of affiliates	5,093	4,847	14,911	14,546
Income (loss) before income taxes	1,654	1,456	5,386	4,462
Provision (benefit) for income taxes	379	528	1,235	1,619
Net income (loss)	1,275	928	4,151	2,843
Net income attributable to noncontrolling interests	22	24	72	74
Net income (loss) attributable to HCA Healthcare, Inc.	1,253	904	4,079	2,769
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	1,258	907	4,091	2,778
Subsidiary Guarantors [Member] | Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	6,747	6,303	20,297	19,008
Subsidiary Non-Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Salaries and benefits	2,287	2,166	6,756	6,189
Supplies	775	744	2,339	2,206
Other operating expenses	958	982	2,931	2,758
Equity in earnings of affiliates	(7)	(12)	(20)	(32)
Depreciation and amortization	242	228	705	658
Interest expense (income)	(64)	(39)	(177)	(124)
Losses (gains) on sales of facilities		(4)	(42)	(4)
Management fees	158	159	473	479
Total expenses including equity in earnings of affiliates	4,349	4,224	12,965	12,130
Income (loss) before income taxes	355	169	1,141	914
Provision (benefit) for income taxes	57	33	185	232
Net income (loss)	298	136	956	682
Net income attributable to noncontrolling interests	115	80	349	286
Net income (loss) attributable to HCA Healthcare, Inc.	183	56	607	396
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	168	76	565	452
Subsidiary Non-Guarantors [Member] | Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	4,704	4,393	14,106	13,044
Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Equity in earnings of affiliates	728	436	2,670	1,702
Total expenses including equity in earnings of affiliates	728	436	2,670	1,702
Income (loss) before income taxes	(728)	(436)	(2,670)	(1,702)
Net income (loss)	(728)	(436)	(2,670)	(1,702)
Net income (loss) attributable to HCA Healthcare, Inc.	(728)	(436)	(2,670)	(1,702)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	$ (723)	$ (461)	$ (2,682)	$ (1,772)