Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ 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
Cash flows from operating activities:
Net income (loss)	$ 1,273	$ 764	$ 927	$ 1,181	$ 1,245	$ 896	$ 966	$ 1,282	$ 4,145	$ 4,389	$ 2,743
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									(88)	33	(296)
Depreciation and amortization									2,596	2,278	2,131
Income taxes									250	74	433
Losses (gains) on sales of facilities									(18)	(428)	(8)
Losses on retirement of debt									211	9	39
Amortization of debt issuance costs									30	31	31
Share-based compensation									347	268	270
Other									129	107	83
Net cash provided by operating activities									7,602	6,761	5,426
Cash flows from investing activities:
Purchase of property and equipment									(4,158)	(3,573)	(3,015)
Acquisition of hospitals and health care entities									(1,682)	(1,253)	(1,212)
Sales of hospitals and health care entities									61	808	25
Change in investments									25	57	(73)
Other									34	60	(4)
Net cash used in investing activities									(5,720)	(3,901)	(4,279)
Cash flows from financing activities:
Issuance of long-term debt									6,451	2,000	1,502
Net change in revolving credit facilities									(560)	(640)	760
Repayment of long-term debt									(5,324)	(1,704)	(753)
Distributions to noncontrolling interests									(542)	(441)	(448)
Payment of debt issuance costs									(73)	(25)	(26)
Payment of dividends									(550)	(487)	0
Repurchases of common stock									(1,031)	(1,530)	(2,051)
Other									(142)	(248)	(45)
Net cash used in financing activities									(1,771)	(3,075)	(1,061)
Effect on exchange rate changes on cash and cash equivalents									8	(15)	0
Change in cash and cash equivalents									119	(230)	86
Cash and cash equivalents at beginning of period				502				732	502	732	646
Cash and cash equivalents at end of period	621				502				621	502	732
HCA Healthcare, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)									3,505	3,787	2,216
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Income taxes									250	74	433
Equity in earnings of affiliates									(3,597)	(3,688)	(2,476)
Other									109	91	78
Net cash provided by operating activities									267	264	251
Cash flows from financing activities:
Payment of dividends									(550)	(487)
Repurchases of common stock									(1,031)	(1,530)	(2,051)
Changes in intercompany balances with affiliates, net									1,457	2,004	1,867
Other									(143)	(252)	(66)
Net cash used in financing activities									(267)	(265)	(250)
Effect on exchange rate changes on cash and cash equivalents									0
Change in cash and cash equivalents										(1)	1
Cash and cash equivalents at beginning of period								1		1	0
Cash and cash equivalents at end of period											1
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)									(3,260)	(2,755)	(1,973)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									(62)	23	(193)
Losses on retirement of debt									211	9	39
Amortization of debt issuance costs									30	31	31
Net cash provided by operating activities									(3,081)	(2,692)	(2,096)
Cash flows from financing activities:
Issuance of long-term debt									6,451	2,000	1,500
Net change in revolving credit facilities									(560)	(640)	760
Repayment of long-term debt									(5,227)	(1,590)	(628)
Payment of debt issuance costs									(73)	(25)	(26)
Changes in intercompany balances with affiliates, net									2,490	2,947	490
Net cash used in financing activities									3,081	2,692	2,096
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)									6,345	5,761	4,028
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									17	(178)	(219)
Depreciation and amortization									1,447	1,335	1,237
Losses (gains) on sales of facilities									(14)	(357)	(2)
Share-based compensation									347	268	270
Other									23	25
Net cash provided by operating activities									8,165	6,854	5,314
Cash flows from investing activities:
Purchase of property and equipment									(2,342)	(2,008)	(1,681)
Acquisition of hospitals and health care entities									(43)	(897)	(26)
Sales of hospitals and health care entities									42	770	14
Change in investments									6	12	(1)
Other									(7)	(9)
Net cash used in investing activities									(2,344)	(2,132)	(1,694)
Cash flows from financing activities:
Repayment of long-term debt									(59)	(72)	(77)
Distributions to noncontrolling interests									(104)	(83)	(140)
Changes in intercompany balances with affiliates, net									(5,714)	(4,505)	(3,404)
Net cash used in financing activities									(5,877)	(4,660)	(3,621)
Change in cash and cash equivalents									(56)	62	(1)
Cash and cash equivalents at beginning of period				174				112	174	112	113
Cash and cash equivalents at end of period	118				174				118	174	112
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)									1,152	1,284	948
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									(43)	188	116
Depreciation and amortization									1,149	943	894
Losses (gains) on sales of facilities									(4)	(71)	(6)
Other									(3)	(9)	5
Net cash provided by operating activities									2,251	2,335	1,957
Cash flows from investing activities:
Purchase of property and equipment									(1,816)	(1,565)	(1,334)
Acquisition of hospitals and health care entities									(1,639)	(356)	(1,186)
Sales of hospitals and health care entities									19	38	11
Change in investments									19	45	(72)
Other									41	69	(4)
Net cash used in investing activities									(3,376)	(1,769)	(2,585)
Cash flows from financing activities:
Issuance of long-term debt											2
Repayment of long-term debt									(38)	(42)	(48)
Distributions to noncontrolling interests									(438)	(358)	(308)
Changes in intercompany balances with affiliates, net									1,767	(446)	1,047
Other									1	4	21
Net cash used in financing activities									1,292	(842)	714
Effect on exchange rate changes on cash and cash equivalents									8	(15)
Change in cash and cash equivalents									175	(291)	86
Cash and cash equivalents at beginning of period				$ 328				$ 619	328	619	533
Cash and cash equivalents at end of period	$ 503				$ 328				503	328	619
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)									(3,597)	(3,688)	(2,476)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates									$ 3,597	$ 3,688	$ 2,476