Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ 811	$ 720
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities	(1,146)	(1,313)
Provision for doubtful accounts	790	646
Depreciation and amortization	479	473
Income taxes	360	438
Gains on sales of facilities	1	(9)
Legal claim costs	12
Amortization of debt issuance costs	10	10
Share-based compensation	65	48
Other	17	5
Net cash provided by operating activities	1,399	1,018
Cash flows from investing activities:
Purchase of property and equipment	(509)	(446)
Acquisition of hospitals and health care entities	(9)	(28)
Disposition of hospitals and health care entities	4	15
Change in investments	11	22
Other	7	5
Net cash used in investing activities	(496)	(432)
Cash flows from financing activities:
Issuance of long-term debt	3,000	1,000
Net change in revolving credit facilities	(930)	(260)
Repayment of long-term debt	(2,011)	(791)
Distributions to noncontrolling interests	(111)	(132)
Payment of debt issuance costs	(22)	(11)
Repurchases of common stock	(621)	(366)
Other	(97)	(6)
Net cash used in financing activities	(792)	(566)
Change in cash and cash equivalents	111	20
Cash and cash equivalents at beginning of period	741	566
Cash and cash equivalents at end of period	852	586
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)	(629)	(623)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates	629	602
HCA Holdings, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	694	591
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities	(36)	17
Income taxes	360	438
Amortization of debt issuance costs		1
Equity in earnings of affiliates	(629)	(602)
Other	19	16
Net cash provided by operating activities	408	440
Cash flows from financing activities:
Repurchases of common stock	(621)	(366)
Changes in intercompany balances with affiliates, net	311	(68)
Other	(97)	(6)
Net cash used in financing activities	(407)	(440)
Change in cash and cash equivalents	1
Cash and cash equivalents at end of period	1
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	(418)	(371)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities	(67)	(79)
Legal claim costs	12
Amortization of debt issuance costs	10	9
Net cash provided by operating activities	(463)	(441)
Cash flows from financing activities:
Issuance of long-term debt	3,000	1,000
Net change in revolving credit facilities	(930)	(260)
Repayment of long-term debt	(1,980)	(771)
Payment of debt issuance costs	(22)	(11)
Changes in intercompany balances with affiliates, net	395	483
Net cash used in financing activities	463	441
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	772	731
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities	(740)	(739)
Provision for doubtful accounts	494	296
Depreciation and amortization	227	230
Gains on sales of facilities	2	(9)
Share-based compensation	65	48
Other	(4)
Net cash provided by operating activities	816	557
Cash flows from investing activities:
Purchase of property and equipment	(161)	(182)
Acquisition of hospitals and health care entities		(10)
Disposition of hospitals and health care entities		14
Change in investments		6
Net cash used in investing activities	(161)	(172)
Cash flows from financing activities:
Repayment of long-term debt	(17)	(12)
Distributions to noncontrolling interests	(16)	(32)
Changes in intercompany balances with affiliates, net	(556)	(317)
Net cash used in financing activities	(589)	(361)
Change in cash and cash equivalents	66	24
Cash and cash equivalents at beginning of period	155	87
Cash and cash equivalents at end of period	221	111
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	392	392
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities	(303)	(512)
Provision for doubtful accounts	296	350
Depreciation and amortization	252	243
Gains on sales of facilities	(1)
Other	2	(11)
Net cash provided by operating activities	638	462
Cash flows from investing activities:
Purchase of property and equipment	(348)	(264)
Acquisition of hospitals and health care entities	(9)	(18)
Disposition of hospitals and health care entities	4	1
Change in investments	11	16
Other	7	5
Net cash used in investing activities	(335)	(260)
Cash flows from financing activities:
Repayment of long-term debt	(14)	(8)
Distributions to noncontrolling interests	(95)	(100)
Changes in intercompany balances with affiliates, net	(150)	(98)
Net cash used in financing activities	(259)	(206)
Change in cash and cash equivalents	44	(4)
Cash and cash equivalents at beginning of period	586	479
Cash and cash equivalents at end of period	$ 630	$ 475