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, 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
Cash flows from operating activities:
Net income (loss)	$ 1,245	$ 896	$ 966	$ 1,282	$ 641	$ 530	$ 795	$ 777	$ 4,389	$ 2,743	$ 3,432
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									33	(296)	42
Depreciation and amortization									2,278	2,131	1,966
Income taxes									74	433	123
Gains on sales of facilities									(428)	(8)	(23)
Losses on retirement of debt									9	39	4
Legal claim benefits											(246)
Amortization of debt issuance costs									31	31	34
Share-based compensation									268	270	251
Other									107	83	70
Net cash provided by (used in) operating activities									6,761	5,426	5,653
Cash flows from investing activities:
Purchase of property and equipment									(3,573)	(3,015)	(2,760)
Acquisition of hospitals and health care entities									(1,253)	(1,212)	(576)
Disposal of hospitals and health care entities									808	25	26
Change in investments									57	(73)	64
Other									60	(4)	6
Net cash used in investing activities									(3,901)	(4,279)	(3,240)
Cash flows from financing activities:
Issuance of long-term debt									2,000	1,502	5,400
Net change in revolving bank credit facilities									(640)	760	(110)
Repayment of long-term debt									(1,704)	(753)	(4,475)
Distributions to noncontrolling interests									(441)	(448)	(434)
Payment of debt issuance costs									(25)	(26)	(40)
Payment of cash dividends									(487)
Repurchases of common stock									(1,530)	(2,051)	(2,751)
Other									(248)	(45)	(98)
Net cash (used in) provided by financing activities									(3,075)	(1,061)	(2,508)
Effect of exchange rate changes on cash and cash equivalents									(15)
Change in cash and cash equivalents									(230)	86	(95)
Cash and cash equivalents at beginning of period				732				646	732	646	741
Cash and cash equivalents at end of period	502				732				502	732	646
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)									(3,688)	(2,476)	(2,738)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates									3,688	2,476	2,738
HCA Healthcare, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)									3,787	2,216	2,890
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities											(25)
Income taxes									74	433	123
Amortization of debt issuance costs											1
Equity in earnings of affiliates									(3,688)	(2,476)	(2,738)
Other									91	78	71
Net cash provided by (used in) operating activities									264	251	322
Cash flows from financing activities:
Payment of cash dividends									(487)
Repurchases of common stock									(1,530)	(2,051)	(2,751)
Changes in intercompany balances with affiliates, net									2,004	1,867	2,532
Other									(252)	(66)	(103)
Net cash (used in) provided by financing activities									(265)	(250)	(322)
Change in cash and cash equivalents									(1)	1
Cash and cash equivalents at beginning of period				1					1
Cash and cash equivalents at end of period					1					1
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)									(2,755)	(1,973)	(1,586)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									23	(193)	39
Losses on retirement of debt									9	39	4
Legal claim benefits											(246)
Amortization of debt issuance costs									31	31	33
Net cash provided by (used in) operating activities									(2,692)	(2,096)	(1,756)
Cash flows from financing activities:
Issuance of long-term debt									2,000	1,500	5,400
Net change in revolving bank credit facilities									(640)	760	(110)
Repayment of long-term debt									(1,590)	(628)	(4,358)
Payment of debt issuance costs									(25)	(26)	(40)
Changes in intercompany balances with affiliates, net									2,947	490	864
Net cash (used in) provided by financing activities									2,692	2,096	1,756
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)									5,761	4,028	3,741
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									(178)	(219)	(139)
Depreciation and amortization									1,335	1,237	1,141
Gains on sales of facilities									(357)	(2)	4
Share-based compensation									268	270	251
Other									25
Net cash provided by (used in) operating activities									6,854	5,314	4,998
Cash flows from investing activities:
Purchase of property and equipment									(2,008)	(1,681)	(1,554)
Acquisition of hospitals and health care entities									(897)	(26)	(199)
Disposal of hospitals and health care entities									770	14	10
Change in investments									12	(1)	(15)
Other									(9)
Net cash used in investing activities									(2,132)	(1,694)	(1,758)
Cash flows from financing activities:
Repayment of long-term debt									(72)	(77)	(74)
Distributions to noncontrolling interests									(83)	(140)	(64)
Changes in intercompany balances with affiliates, net									(4,505)	(3,404)	(3,149)
Net cash (used in) provided by financing activities									(4,660)	(3,621)	(3,287)
Change in cash and cash equivalents									62	(1)	(47)
Cash and cash equivalents at beginning of period				112				113	112	113	160
Cash and cash equivalents at end of period	174				112				174	112	113
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)									1,284	948	1,125
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Change in operating assets and liabilities									188	116	167
Depreciation and amortization									943	894	825
Gains on sales of facilities									(71)	(6)	(27)
Other									(9)	5	(1)
Net cash provided by (used in) operating activities									2,335	1,957	2,089
Cash flows from investing activities:
Purchase of property and equipment									(1,565)	(1,334)	(1,206)
Acquisition of hospitals and health care entities									(356)	(1,186)	(377)
Disposal of hospitals and health care entities									38	11	16
Change in investments									45	(72)	79
Other									69	(4)	6
Net cash used in investing activities									(1,769)	(2,585)	(1,482)
Cash flows from financing activities:
Issuance of long-term debt										2
Repayment of long-term debt									(42)	(48)	(43)
Distributions to noncontrolling interests									(358)	(308)	(370)
Changes in intercompany balances with affiliates, net									(446)	1,047	(247)
Other									4	21	5
Net cash (used in) provided by financing activities									(842)	714	(655)
Effect of exchange rate changes on cash and cash equivalents									(15)
Change in cash and cash equivalents									(291)	86	(48)
Cash and cash equivalents at beginning of period				$ 619				$ 533	619	533	581
Cash and cash equivalents at end of period	$ 328				$ 619				$ 328	$ 619	$ 533