Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Schedule of Condensed Consolidating Comprehensive Income Statement (Detail) - USD ($) $ 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
Condensed Statement of Income Captions [Line Items]
Revenues	$ 12,274	$ 11,451	$ 11,529	$ 11,423	$ 11,562	$ 10,696	$ 10,733	$ 10,623	$ 46,677	$ 43,614	$ 41,490
Salaries and benefits									21,425	20,059	18,897
Supplies									7,724	7,316	6,933
Other operating expenses									8,608	8,051	7,496
Equity in earnings of affiliates									(29)	(45)	(54)
Depreciation and amortization									2,278	2,131	1,966
Interest expense (income)									1,755	1,690	1,707
Losses (gains) on sales of facilities									(428)	(8)	(23)
Losses on retirement of debt									9	39	4
Legal claim benefits											(246)
Total expenses including equity in earnings of affiliates									41,342	39,233	36,680
Income (loss) before income taxes									5,335	4,381	4,810
Provision (benefit) for income taxes									946	1,638	1,378
Net income (loss)	1,245	896	966	1,282	641	530	795	777	4,389	2,743	3,432
Net income attributable to noncontrolling interests									602	527	542
Net income (loss) attributable to HCA Healthcare, Inc.	$ 1,064	$ 759	$ 820	$ 1,144	$ 474	$ 426	$ 657	$ 659	3,787	2,216	2,890
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									3,779	2,276	2,817
HCA Healthcare, Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Other operating expenses									8	6	6
Equity in earnings of affiliates									(3,688)	(2,476)	(2,738)
Interest expense (income)									64	64	64
Total expenses including equity in earnings of affiliates									(3,616)	(2,406)	(2,668)
Income (loss) before income taxes									3,616	2,406	2,668
Provision (benefit) for income taxes									(171)	190	(222)
Net income (loss)									3,787	2,216	2,890
Net income (loss) attributable to HCA Healthcare, Inc.									3,787	2,216	2,890
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									3,779	2,276	2,817
HCA Inc. Issuer [Member]
Condensed Statement of Income Captions [Line Items]
Interest expense (income)									3,580	3,088	2,756
Losses on retirement of debt									9	39	4
Legal claim benefits											(246)
Total expenses including equity in earnings of affiliates									3,589	3,127	2,514
Income (loss) before income taxes									(3,589)	(3,127)	(2,514)
Provision (benefit) for income taxes									(834)	(1,154)	(928)
Net income (loss)									(2,755)	(1,973)	(1,586)
Net income (loss) attributable to HCA Healthcare, Inc.									(2,755)	(1,973)	(1,586)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									(2,745)	(1,953)	(1,505)
Subsidiary Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Revenues									27,482	25,774	24,427
Salaries and benefits									12,287	11,619	10,971
Supplies									4,560	4,286	4,090
Other operating expenses									4,463	4,249	3,912
Equity in earnings of affiliates									(7)	(6)	(7)
Depreciation and amortization									1,335	1,237	1,141
Interest expense (income)									(1,635)	(1,309)	(970)
Losses (gains) on sales of facilities									(357)	(2)	4
Management fees									(639)	(621)	(588)
Total expenses including equity in earnings of affiliates									20,007	19,453	18,553
Income (loss) before income taxes									7,475	6,321	5,874
Provision (benefit) for income taxes									1,714	2,293	2,133
Net income (loss)									5,761	4,028	3,741
Net income attributable to noncontrolling interests									99	108	93
Net income (loss) attributable to HCA Healthcare, Inc.									5,662	3,920	3,648
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									5,712	3,898	3,637
Subsidiary Non-Guarantors [Member]
Condensed Statement of Income Captions [Line Items]
Revenues									19,195	17,840	17,063
Salaries and benefits									9,138	8,440	7,926
Supplies									3,164	3,030	2,843
Other operating expenses									4,137	3,796	3,578
Equity in earnings of affiliates									(22)	(39)	(47)
Depreciation and amortization									943	894	825
Interest expense (income)									(254)	(153)	(143)
Losses (gains) on sales of facilities									(71)	(6)	(27)
Management fees									639	621	588
Total expenses including equity in earnings of affiliates									17,674	16,583	15,543
Income (loss) before income taxes									1,521	1,257	1,520
Provision (benefit) for income taxes									237	309	395
Net income (loss)									1,284	948	1,125
Net income attributable to noncontrolling interests									503	419	449
Net income (loss) attributable to HCA Healthcare, Inc.									781	529	676
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									713	591	533
Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Equity in earnings of affiliates									3,688	2,476	2,738
Total expenses including equity in earnings of affiliates									3,688	2,476	2,738
Income (loss) before income taxes									(3,688)	(2,476)	(2,738)
Net income (loss)									(3,688)	(2,476)	(2,738)
Net income (loss) attributable to HCA Healthcare, Inc.									(3,688)	(2,476)	(2,738)
Comprehensive income (loss) attributable to HCA Healthcare, Inc.									$ (3,680)	$ (2,536)	$ (2,665)