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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income (loss)	$ 745	$ 573	$ 2,347	$ 1,958
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(2,546)	(3,333)
Provision for doubtful accounts	840	1,158	2,392	2,839
Depreciation and amortization	495	482	1,463	1,424
Income taxes			8	(148)
Losses (gains) on sales of facilities	(3)	2	(8)	(2)
Losses on retirement of debt	4		4	125
Legal claim costs			33	77
Amortization of debt issuance costs			26	27
Share-based compensation			196	171
Other			39	38
Net cash provided by operating activities			3,954	3,176
Cash flows from investing activities:
Purchase of property and equipment			(1,884)	(1,571)
Acquisition of hospitals and health care entities			(468)	(184)
Disposition of hospitals and health care entities			23	27
Change in investments			78	94
Other			17	3
Net cash used in investing activities			(2,234)	(1,631)
Cash flows from financing activities:
Issuance of long-term debt			5,400	4,048
Net change in revolving credit facilities			(70)	(270)
Repayment of long-term debt			(4,424)	(3,702)
Distributions to noncontrolling interests			(342)	(367)
Payment of debt issuance costs			(40)	(34)
Repurchases of common stock			(2,213)	(1,386)
Other			(95)	188
Net cash (used in) provided by financing activities			(1,784)	(1,523)
Change in cash and cash equivalents			(64)	22
Cash and cash equivalents at beginning of period			741	566
Cash and cash equivalents at end of period	677	588	677	588
Eliminations [Member]
Cash flows from operating activities:
Net income (loss)	(573)	(464)	(1,843)	(1,690)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Equity in earnings of affiliates			1,843	1,690
HCA Holdings, Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	618	449	1,970	1,547
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(40)	(22)
Income taxes			8	(148)
Losses on retirement of debt				122
Amortization of debt issuance costs				3
Equity in earnings of affiliates			(1,843)	(1,690)
Other			53	49
Net cash provided by operating activities			148	(139)
Cash flows from financing activities:
Repayment of long-term debt				(1,632)
Repurchases of common stock			(2,213)	(1,386)
Changes in intercompany balances with affiliates, net			2,171	2,955
Other			(105)	202
Net cash (used in) provided by financing activities			(147)	139
Change in cash and cash equivalents			1
Cash and cash equivalents at end of period	1		1
HCA Inc. Issuer [Member]
Cash flows from operating activities:
Net income (loss)	(458)	(427)	(1,305)	(1,171)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(49)	(56)
Losses on retirement of debt	4		4	3
Legal claim costs			33	77
Amortization of debt issuance costs			26	24
Other				3
Net cash provided by operating activities			(1,291)	(1,120)
Cash flows from financing activities:
Issuance of long-term debt			5,400	4,048
Net change in revolving credit facilities			(70)	(270)
Repayment of long-term debt			(4,334)	(2,001)
Payment of debt issuance costs			(40)	(34)
Changes in intercompany balances with affiliates, net			335	(623)
Net cash (used in) provided by financing activities			1,291	1,120
Subsidiary Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	788	675	2,371	2,166
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(1,628)	(1,959)
Provision for doubtful accounts	391	689	1,383	1,535
Depreciation and amortization	242	230	707	683
Losses (gains) on sales of facilities		(1)		(5)
Share-based compensation			196	171
Other			(3)
Net cash provided by operating activities			3,026	2,591
Cash flows from investing activities:
Purchase of property and equipment			(892)	(764)
Acquisition of hospitals and health care entities			(164)	(51)
Disposition of hospitals and health care entities			10	19
Change in investments			(2)	2
Other				(6)
Net cash used in investing activities			(1,048)	(800)
Cash flows from financing activities:
Repayment of long-term debt			(54)	(45)
Distributions to noncontrolling interests			(46)	(70)
Changes in intercompany balances with affiliates, net			(1,895)	(1,654)
Net cash (used in) provided by financing activities			(1,995)	(1,769)
Change in cash and cash equivalents			(17)	22
Cash and cash equivalents at beginning of period			155	87
Cash and cash equivalents at end of period	138	109	138	109
Subsidiary Non-Guarantors [Member]
Cash flows from operating activities:
Net income (loss)	370	340	1,154	1,106
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Changes in operating assets and liabilities			(829)	(1,296)
Provision for doubtful accounts	449	469	1,009	1,304
Depreciation and amortization	253	252	756	741
Losses (gains) on sales of facilities	(3)	3	(8)	3
Other			(11)	(14)
Net cash provided by operating activities			2,071	1,844
Cash flows from investing activities:
Purchase of property and equipment			(992)	(807)
Acquisition of hospitals and health care entities			(304)	(133)
Disposition of hospitals and health care entities			13	8
Change in investments			80	92
Other			17	9
Net cash used in investing activities			(1,186)	(831)
Cash flows from financing activities:
Repayment of long-term debt			(36)	(24)
Distributions to noncontrolling interests			(296)	(297)
Changes in intercompany balances with affiliates, net			(611)	(678)
Other			10	(14)
Net cash (used in) provided by financing activities			(933)	(1,013)
Change in cash and cash equivalents			(48)
Cash and cash equivalents at beginning of period			586	479
Cash and cash equivalents at end of period	$ 538	$ 479	$ 538	$ 479