Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Comprehensive Income Statement (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
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts	$ 11,014	$ 9,978			$ 32,268	$ 29,619
Provision for doubtful accounts	1,158	758			2,839	2,337
Revenues	9,856	9,220			29,429	27,282
Salaries and benefits	4,619	4,211			13,509	12,359
Supplies	1,644	1,539			4,952	4,603
Other operating expenses	1,796	1,688			5,268	4,977
Electronic health record incentive income	(9)	(32)			(46)	(97)
Equity in earnings of affiliates	(9)	(14)			(38)	(32)
Depreciation and amortization	482	460			1,424	1,361
Interest expense (revenue)	411	427			1,255	1,314
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
Total expenses including equity in earnings of affiliates	9,013	8,291			26,524	24,769
Income (loss) before income taxes	843	929			2,905	2,513
Provision (benefit) for income taxes	270	318			947	816
Net income (loss)	573	611			1,958	1,697
Net income attributable to noncontrolling interests	124	93			411	349
Net income (loss) attributable to HCA Holdings, Inc.	449	518			1,547	1,348
Comprehensive income (loss) attributable to HCA Holdings, Inc.	430	511			1,561	1,399
HCA Holdings, Inc. Issuer [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Other operating expenses	7	4			9	14
Equity in earnings of affiliates	(464)	(549)			(1,690)	(1,443)
Interest expense (revenue)	16	46			100	138
Losses on retirement of debt					122
Total expenses including equity in earnings of affiliates	(441)	(499)			(1,459)	(1,291)
Income (loss) before income taxes	441	499			1,459	1,291
Provision (benefit) for income taxes	(8)	(19)			(88)	(57)
Net income (loss)	449	518			1,547	1,348
Net income (loss) attributable to HCA Holdings, Inc.	449	518			1,547	1,348
Comprehensive income (loss) attributable to HCA Holdings, Inc.	430	511			1,561	1,399
HCA Inc. Issuer [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Interest expense (revenue)	608	536			1,807	1,629
Losses on retirement of debt					3	226
Legal claim costs	77				77	78
Total expenses including equity in earnings of affiliates	685	536			1,887	1,933
Income (loss) before income taxes	(685)	(536)			(1,887)	(1,933)
Provision (benefit) for income taxes	(258)	(205)			(716)	(729)
Net income (loss)	(427)	(331)			(1,171)	(1,204)
Net income (loss) attributable to HCA Holdings, Inc.	(427)	(331)			(1,171)	(1,204)
Comprehensive income (loss) attributable to HCA Holdings, Inc.	(418)	(303)			(1,142)	(1,154)
Subsidiary Guarantors [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts	5,721	5,133			16,519	15,242
Provision for doubtful accounts	689	457			1,535	1,388
Revenues	5,032	4,676			14,984	13,854
Salaries and benefits	2,357	2,176			6,824	6,393
Supplies	853	797			2,576	2,416
Other operating expenses	865	804			2,523	2,366
Electronic health record incentive income	(6)	(22)			(31)	(68)
Equity in earnings of affiliates	(1)	(3)			(4)	(5)
Depreciation and amortization	230	225			683	667
Interest expense (revenue)	(156)	(115)			(498)	(349)
Losses (gains) on sales of facilities	(1)	16			(5)	(16)
Management fee revenue	(178)	(178)			(534)	(528)
Total expenses including equity in earnings of affiliates	3,963	3,700			11,534	10,876
Income (loss) before income taxes	1,069	976			3,450	2,978
Provision (benefit) for income taxes	394	365			1,284	1,098
Net income (loss)	675	611			2,166	1,880
Net income attributable to noncontrolling interests	21	18			68	65
Net income (loss) attributable to HCA Holdings, Inc.	654	593			2,098	1,815
Comprehensive income (loss) attributable to HCA Holdings, Inc.	657	595			2,109	1,822
Subsidiary Non-Guarantors [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts	5,293	4,845			15,749	14,377
Provision for doubtful accounts	469	301			1,304	949
Revenues	4,824	4,544			14,445	13,428
Salaries and benefits	2,262	2,035			6,685	5,966
Supplies	791	742			2,376	2,187
Other operating expenses	924	880			2,736	2,597
Electronic health record incentive income	(3)	(10)			(15)	(29)
Equity in earnings of affiliates	(8)	(11)			(34)	(27)
Depreciation and amortization	252	235			741	694
Interest expense (revenue)	(57)	(40)			(154)	(104)
Losses (gains) on sales of facilities	3	(4)			3	(4)
Management fee expense	178	178			534	528
Total expenses including equity in earnings of affiliates	4,342	4,005			12,872	11,808
Income (loss) before income taxes	482	539			1,573	1,620
Provision (benefit) for income taxes	142	177			467	504
Net income (loss)	340	362			1,106	1,116
Net income attributable to noncontrolling interests	103	75			343	284
Net income (loss) attributable to HCA Holdings, Inc.	237	287			763	832
Comprehensive income (loss) attributable to HCA Holdings, Inc.	206	250			737	826
Eliminations [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Equity in earnings of affiliates	464	549			1,690	1,443
Total expenses including equity in earnings of affiliates	464	549			1,690	1,443
Income (loss) before income taxes	(464)	(549)			(1,690)	(1,443)
Net income (loss)	(464)	(549)			(1,690)	(1,443)
Net income (loss) attributable to HCA Holdings, Inc.	(464)	(549)			(1,690)	(1,443)
Comprehensive income (loss) attributable to HCA Holdings, Inc.	$ (445)	$ (542)			$ (1,704)	$ (1,494)