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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 795	$ 791	$ 1,572	$ 1,602
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(2,228)	(1,642)
Provision for doubtful accounts	1,073	762	1,833	1,552
Depreciation and amortization	521	489	1,042	968
Income taxes			267	67
Gains on sales of facilities	(2)	(6)	(3)	(5)
Legal claim costs		10		22
Amortization of debt issuance costs			16	18
Share-based compensation			140	129
Other			45	37
Net cash provided by (used in) operating activities			2,684	2,748
Cash flows from investing activities:
Purchase of property and equipment			(1,304)	(1,172)
Acquisition of hospitals and health care entities			(295)	(430)
Disposition of hospitals and health care entities			14	14
Change in investments			(11)	18
Other			5	15
Net cash used in investing activities			(1,591)	(1,555)
Cash flows from financing activities:
Issuance of long-term debt			1,502	3,000
Net change in revolving credit facilities			(1,160)
Repayment of long-term debt			(95)	(2,065)
Distributions to noncontrolling interests			(248)	(205)
Payment of debt issuance costs			(25)	(24)
Repurchases of common stock			(966)	(1,858)
Other			(42)	(91)
Net cash (used in) provided by financing activities			(1,034)	(1,243)
Change in cash and cash equivalents			59	(50)
Cash and cash equivalents at beginning of period			646	741
Cash and cash equivalents at end of period	705	691	705	691
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)	(658)	(641)	(1,266)	(1,270)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates			1,266	1,270
HCA Healthcare, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	657	658	1,316	1,352
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			1	(23)
Income taxes			267	67
Equity in earnings of affiliates			(1,266)	(1,270)
Other			39	37
Net cash provided by (used in) operating activities			357	163
Cash flows from financing activities:
Repurchases of common stock			(966)	(1,858)
Changes in intercompany balances with affiliates, net			671	1,799
Other			(62)	(104)
Net cash (used in) provided by financing activities			(357)	(163)
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	(476)	(429)	(939)	(847)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(189)	66
Legal claim costs		10		22
Amortization of debt issuance costs			16	18
Net cash provided by (used in) operating activities			(1,112)	(741)
Cash flows from financing activities:
Issuance of long-term debt			1,500	3,000
Net change in revolving credit facilities			(1,160)
Repayment of long-term debt			(42)	(2,005)
Payment of debt issuance costs			(25)	(24)
Changes in intercompany balances with affiliates, net			839	(230)
Net cash (used in) provided by financing activities			1,112	741
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	889	811	1,730	1,583
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(1,189)	(1,140)
Provision for doubtful accounts	593	498	1,012	992
Depreciation and amortization	248	238	499	465
Gains on sales of facilities	(1)	(2)	(1)
Share-based compensation			140	129
Other				(2)
Net cash provided by (used in) operating activities			2,191	2,027
Cash flows from investing activities:
Purchase of property and equipment			(578)	(482)
Acquisition of hospitals and health care entities			(5)	(148)
Disposition of hospitals and health care entities			10	9
Change in investments				3
Other			2	(1)
Net cash used in investing activities			(571)	(619)
Cash flows from financing activities:
Repayment of long-term debt			(33)	(38)
Distributions to noncontrolling interests			(79)	(29)
Changes in intercompany balances with affiliates, net			(1,463)	(1,414)
Net cash (used in) provided by financing activities			(1,575)	(1,481)
Change in cash and cash equivalents			45	(73)
Cash and cash equivalents at beginning of period			110	155
Cash and cash equivalents at end of period	155	82	155	82
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	383	392	731	784
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(851)	(545)
Provision for doubtful accounts	480	264	821	560
Depreciation and amortization	273	251	543	503
Gains on sales of facilities	(1)	(4)	(2)	(5)
Other			6	2
Net cash provided by (used in) operating activities			1,248	1,299
Cash flows from investing activities:
Purchase of property and equipment			(726)	(690)
Acquisition of hospitals and health care entities			(290)	(282)
Disposition of hospitals and health care entities			4	5
Change in investments			(11)	15
Other			3	16
Net cash used in investing activities			(1,020)	(936)
Cash flows from financing activities:
Issuance of long-term debt			2
Repayment of long-term debt			(20)	(22)
Distributions to noncontrolling interests			(169)	(176)
Changes in intercompany balances with affiliates, net			(47)	(155)
Other			20	13
Net cash (used in) provided by financing activities			(214)	(340)
Change in cash and cash equivalents			14	23
Cash and cash equivalents at beginning of period			536	586
Cash and cash equivalents at end of period	$ 550	$ 609	$ 550	$ 609