Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2012	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income (loss)	$ 573	$ 611			$ 1,958	$ 1,697
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(3,333)	(2,945)
Provision for doubtful accounts					2,839	2,337
Depreciation and amortization	482	460			1,424	1,361
Income taxes					(148)	(61)
Losses (gains) on sales of facilities	2	12			(2)	(20)
Losses on retirement of debt					125	226
Legal claim costs	77		$ 78	$ 175	77	78
Amortization of debt issuance costs					27	33
Share-based compensation					171	118
Equity in earnings of affiliates	(9)	(14)			(38)	(32)
Other					38	(3)
Net cash provided by operating activities					3,176	2,821
Cash flows from investing activities:
Purchase of property and equipment					(1,571)	(1,482)
Acquisition of hospitals and health care entities					(184)	(97)
Disposition of hospitals and health care entities					27	38
Change in investments					94	22
Other					3	7
Net cash used in investing activities					(1,631)	(1,512)
Cash flows from financing activities:
Issuance of long-term debt					4,048	3,502
Net change in revolving credit facilities					(270)	(160)
Repayment of long-term debt					(3,702)	(3,525)
Distributions to noncontrolling interests					(367)	(325)
Payment of debt issuance costs					(34)	(49)
Repurchases of common stock					(1,386)	(750)
Income tax benefits					231	119
Other					(43)	(20)
Net cash used in financing activities					(1,523)	(1,208)
Change in cash and cash equivalents					22	101
Cash and cash equivalents at beginning of period			414		566	414
Cash and cash equivalents at end of period	588	515			588	515
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)	(464)	(549)			(1,690)	(1,443)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates	464	549			1,690	1,443
HCA Holdings, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	449	518			1,547	1,348
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(22)	18
Income taxes					(148)	(61)
Losses on retirement of debt					122
Amortization of debt issuance costs					3	2
Share-based compensation					171	118
Equity in earnings of affiliates	(464)	(549)			(1,690)	(1,443)
Other					49
Net cash provided by operating activities					32	(18)
Cash flows from financing activities:
Repayment of long-term debt					(1,632)
Repurchases of common stock					(1,386)	(750)
Changes in intercompany balances with affiliates, net					2,784	654
Income tax benefits					231	119
Other					(29)	(5)
Net cash used in financing activities					(32)	18
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	(427)	(331)			(1,171)	(1,204)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(56)	(151)
Losses on retirement of debt					3	226
Legal claim costs	77				77	78
Amortization of debt issuance costs					24	31
Other					3	3
Net cash provided by operating activities					(1,120)	(1,017)
Cash flows from financing activities:
Issuance of long-term debt					4,048	3,502
Net change in revolving credit facilities					(270)	(160)
Repayment of long-term debt					(2,001)	(3,462)
Payment of debt issuance costs					(34)	(49)
Changes in intercompany balances with affiliates, net					(623)	1,186
Net cash used in financing activities					1,120	1,017
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	675	611			2,166	1,880
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(1,959)	(1,660)
Provision for doubtful accounts					1,535	1,388
Depreciation and amortization	230	225			683	667
Losses (gains) on sales of facilities	(1)	16			(5)	(16)
Equity in earnings of affiliates	(1)	(3)			(4)	(5)
Net cash provided by operating activities					2,420	2,259
Cash flows from investing activities:
Purchase of property and equipment					(764)	(893)
Acquisition of hospitals and health care entities					(51)	(7)
Disposition of hospitals and health care entities					19	31
Change in investments					2	22
Other					(6)
Net cash used in investing activities					(800)	(847)
Cash flows from financing activities:
Repayment of long-term debt					(45)	(35)
Distributions to noncontrolling interests					(70)	(45)
Changes in intercompany balances with affiliates, net					(1,483)	(1,331)
Net cash used in financing activities					(1,598)	(1,411)
Change in cash and cash equivalents					22	1
Cash and cash equivalents at beginning of period			112		87	112
Cash and cash equivalents at end of period	109	113			109	113
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	340	362			1,106	1,116
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities					(1,296)	(1,152)
Provision for doubtful accounts					1,304	949
Depreciation and amortization	252	235			741	694
Losses (gains) on sales of facilities	3	(4)			3	(4)
Equity in earnings of affiliates	(8)	(11)			(34)	(27)
Other					(14)	(6)
Net cash provided by operating activities					1,844	1,597
Cash flows from investing activities:
Purchase of property and equipment					(807)	(589)
Acquisition of hospitals and health care entities					(133)	(90)
Disposition of hospitals and health care entities					8	7
Change in investments					92
Other					9	7
Net cash used in investing activities					(831)	(665)
Cash flows from financing activities:
Repayment of long-term debt					(24)	(28)
Distributions to noncontrolling interests					(297)	(280)
Changes in intercompany balances with affiliates, net					(678)	(509)
Other					(14)	(15)
Net cash used in financing activities					(1,013)	(832)
Change in cash and cash equivalents						100
Cash and cash equivalents at beginning of period			$ 302		479	302
Cash and cash equivalents at end of period	$ 479	$ 402			$ 479	$ 402