Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Schedule of Condensed Consolidating Comprehensive Income Statement (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Statement of Income Captions [Line Items]
Revenues	$ 11,529	$ 10,733	$ 22,952	$ 21,356
Salaries and benefits	5,274	4,896	10,563	9,797
Supplies	1,917	1,795	3,832	3,592
Other operating expenses	2,118	1,965	4,228	3,895
Equity in earnings of affiliates	(7)	(13)	(16)	(23)
Depreciation and amortization	562	521	1,115	1,042
Interest expense	436	411	867	830
Losses (gains) on sales of facilities	(9)	(2)	(414)	(3)
Total expenses including equity in earnings of affiliates	10,291	9,573	20,175	19,130
Income (loss) before income taxes	1,238	1,160	2,777	2,226
Provision (benefit) for income taxes	272	365	529	654
Net income (loss)	966	795	2,248	1,572
Net income attributable to noncontrolling interests	146	138	284	256
Net income (loss) attributable to HCA Healthcare, Inc.	820	657	1,964	1,316
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	756	684	1,981	1,361
Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	11,529	10,733	22,952	21,356
HCA Healthcare, Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Other operating expenses	4	4	5	5
Equity in earnings of affiliates	(852)	(658)	(1,942)	(1,266)
Interest expense	16	16	32	32
Total expenses including equity in earnings of affiliates	(832)	(638)	(1,905)	(1,229)
Income (loss) before income taxes	832	638	1,905	1,229
Provision (benefit) for income taxes	12	(19)	(59)	(87)
Net income (loss)	820	657	1,964	1,316
Net income (loss) attributable to HCA Healthcare, Inc.	820	657	1,964	1,316
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	756	684	1,981	1,361
HCA Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Interest expense	867	755	1,704	1,488
Total expenses including equity in earnings of affiliates	867	755	1,704	1,488
Income (loss) before income taxes	(867)	(755)	(1,704)	(1,488)
Provision (benefit) for income taxes	(201)	(279)	(396)	(549)
Net income (loss)	(666)	(476)	(1,308)	(939)
Net income (loss) attributable to HCA Healthcare, Inc.	(666)	(476)	(1,308)	(939)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	(656)	(480)	(1,271)	(936)
Subsidiary Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Salaries and benefits	3,025	2,870	6,094	5,774
Supplies	1,127	1,055	2,268	2,130
Other operating expenses	1,122	1,064	2,250	2,114
Equity in earnings of affiliates	(1)	(1)	(3)	(3)
Depreciation and amortization	329	302	652	612
Interest expense	(389)	(315)	(756)	(605)
Losses (gains) on sales of facilities	23	(4)	(372)	(3)
Management fees	(157)	(160)	(315)	(320)
Total expenses including equity in earnings of affiliates	5,079	4,811	9,818	9,699
Income (loss) before income taxes	1,695	1,558	3,732	3,006
Provision (benefit) for income taxes	389	565	856	1,091
Net income (loss)	1,306	993	2,876	1,915
Net income attributable to noncontrolling interests	22	27	50	50
Net income (loss) attributable to HCA Healthcare, Inc.	1,284	966	2,826	1,865
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	1,287	969	2,833	1,871
Subsidiary Guarantors [Member] | Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	6,774	6,369	13,550	12,705
Subsidiary Non-Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Salaries and benefits	2,249	2,026	4,469	4,023
Supplies	790	740	1,564	1,462
Other operating expenses	992	897	1,973	1,776
Equity in earnings of affiliates	(6)	(12)	(13)	(20)
Depreciation and amortization	233	219	463	430
Interest expense	(58)	(45)	(113)	(85)
Losses (gains) on sales of facilities	(32)	2	(42)
Management fees	157	160	315	320
Total expenses including equity in earnings of affiliates	4,325	3,987	8,616	7,906
Income (loss) before income taxes	430	377	786	745
Provision (benefit) for income taxes	72	98	128	199
Net income (loss)	358	279	658	546
Net income attributable to noncontrolling interests	124	111	234	206
Net income (loss) attributable to HCA Healthcare, Inc.	234	168	424	340
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	157	196	397	376
Subsidiary Non-Guarantors [Member] | Health Care, Patient Service [Member]
Condensed Statement of Income Captions [Line Items]
Revenues	4,755	4,364	9,402	8,651
Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Equity in earnings of affiliates	852	658	1,942	1,266
Total expenses including equity in earnings of affiliates	852	658	1,942	1,266
Income (loss) before income taxes	(852)	(658)	(1,942)	(1,266)
Net income (loss)	(852)	(658)	(1,942)	(1,266)
Net income (loss) attributable to HCA Healthcare, Inc.	(852)	(658)	(1,942)	(1,266)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.	$ (788)	$ (685)	$ (1,959)	$ (1,311)