Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Comprehensive Income Statement (Detail) - USD ($) $ in Millions		3 Months Ended
	Dec. 09, 2015	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2012
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts		$ 11,050		$ 10,322
Provision for doubtful accounts		790		646
Revenues		10,260		9,676
Salaries and benefits		4,702		4,398
Supplies		1,714		1,638
Other operating expenses		1,857		1,717
Electronic health record incentive income		(4)		(19)
Equity in earnings of affiliates		(12)		(19)
Depreciation and amortization		479		473
Interest expense (revenue)		416		419
Losses (gains) on sales of facilities		1		(9)
Legal claim costs	$ 434	12	$ 120		$ 78	$ 175
Total expenses including equity in earnings of affiliates		9,165		8,598
Income (loss) before income taxes		1,095		1,078
Provision (benefit) for income taxes		284		358
Net income (loss)		811		720
Net income attributable to noncontrolling interests		117		129
Net income (loss) attributable to HCA Holdings, Inc.		694		591
Comprehensive income (loss) attributable to HCA Holdings, Inc.		665		570
HCA Holdings, Inc. Issuer [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Other operating expenses		2		6
Equity in earnings of affiliates		(629)		(623)
Interest expense (revenue)		16		46
Total expenses including equity in earnings of affiliates		(611)		(571)
Income (loss) before income taxes		611		571
Provision (benefit) for income taxes		(83)		(20)
Net income (loss)		694		591
Net income (loss) attributable to HCA Holdings, Inc.		694		591
Comprehensive income (loss) attributable to HCA Holdings, Inc.		665		570
HCA Inc. Issuer [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Interest expense (revenue)		650		595
Legal claim costs		12
Total expenses including equity in earnings of affiliates		662		595
Income (loss) before income taxes		(662)		(595)
Provision (benefit) for income taxes		(244)		(224)
Net income (loss)		(418)		(371)
Net income (loss) attributable to HCA Holdings, Inc.		(418)		(371)
Comprehensive income (loss) attributable to HCA Holdings, Inc.		(425)		(366)
Subsidiary Guarantors [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts		5,673		5,201
Provision for doubtful accounts		494		296
Revenues		5,179		4,905
Salaries and benefits		2,354		2,217
Supplies		898		854
Other operating expenses		860		820
Electronic health record incentive income		(3)		(13)
Equity in earnings of affiliates		(2)		(1)
Depreciation and amortization		227		230
Interest expense (revenue)		(207)		(174)
Losses (gains) on sales of facilities		2		(9)
Management fees		(160)		(178)
Total expenses including equity in earnings of affiliates		3,969		3,746
Income (loss) before income taxes		1,210		1,159
Provision (benefit) for income taxes		438		428
Net income (loss)		772		731
Net income attributable to noncontrolling interests		22		23
Net income (loss) attributable to HCA Holdings, Inc.		750		708
Comprehensive income (loss) attributable to HCA Holdings, Inc.		752		712
Subsidiary Non-Guarantors [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Revenues before provision for doubtful accounts		5,377		5,121
Provision for doubtful accounts		296		350
Revenues		5,081		4,771
Salaries and benefits		2,348		2,181
Supplies		816		784
Other operating expenses		995		891
Electronic health record incentive income		(1)		(6)
Equity in earnings of affiliates		(10)		(18)
Depreciation and amortization		252		243
Interest expense (revenue)		(43)		(48)
Losses (gains) on sales of facilities		(1)
Management fees		160		178
Total expenses including equity in earnings of affiliates		4,516		4,205
Income (loss) before income taxes		565		566
Provision (benefit) for income taxes		173		174
Net income (loss)		392		392
Net income attributable to noncontrolling interests		95		106
Net income (loss) attributable to HCA Holdings, Inc.		297		286
Comprehensive income (loss) attributable to HCA Holdings, Inc.		273		256
Eliminations [Member]
Supplemental Condensed Consolidating Financial Information [Line Items]
Equity in earnings of affiliates		629		623
Total expenses including equity in earnings of affiliates		629		623
Income (loss) before income taxes		(629)		(623)
Net income (loss)		(629)		(623)
Net income (loss) attributable to HCA Holdings, Inc.		(629)		(623)
Comprehensive income (loss) attributable to HCA Holdings, Inc.		$ (600)		$ (602)