Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 588	$ 566	$ 515	$ 414
Accounts receivable, net	5,827	5,694
Inventories	1,379	1,279
Deferred income taxes	412	366
Other	1,015	1,025
Total current assets	9,221	8,930
Property and equipment, net	14,704	14,355
Investments of insurance subsidiaries	409	494
Investments in and advances to affiliates	186	165
Goodwill and other intangible assets	6,540	6,416
Other	836	620
Total assets	31,896	30,980
Current liabilities:
Accounts payable	1,877	2,035
Accrued salaries	1,358	1,370
Other accrued expenses	1,701	1,737
Long-term debt due within one year	1,377	338
Total current liabilities	6,313	5,480
Long-term debt, net	28,375	29,088
Professional liability risks	1,117	1,078
Income taxes and other liabilities	1,903	1,832
Total liabilities	37,708	37,478
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(7,294)	(7,894)
Noncontrolling interests	1,482	1,396
Total stockholders' deficit	(5,812)	(6,498)
Total liabilities and stockholders' deficit	31,896	30,980
HCA Holdings, Inc. Issuer [Member]
Current assets:
Deferred income taxes	412	366
Other	13	118
Total current assets	425	484
Investments in and advances to affiliates	23,674	21,970
Other	625	435
Total assets	24,724	22,889
Current liabilities:
Accounts payable	9	1
Other accrued expenses	14	45
Total current liabilities	23	46
Long-term debt, net	982	2,499
Intercompany balances	30,472	27,685
Income taxes and other liabilities	541	553
Total liabilities	32,018	30,783
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(7,294)	(7,894)
Total stockholders' deficit	(7,294)	(7,894)
Total liabilities and stockholders' deficit	24,724	22,889
HCA Inc. Issuer [Member]
Current liabilities:
Other accrued expenses	245	317
Long-term debt due within one year	1,264	231
Total current liabilities	1,509	548
Long-term debt, net	26,874	26,124
Intercompany balances	(10,757)	(10,141)
Income taxes and other liabilities	534	487
Total liabilities	18,160	17,018
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(18,160)	(17,018)
Total stockholders' deficit	(18,160)	(17,018)
Subsidiary Guarantors [Member]
Current assets:
Cash and cash equivalents	109	87	113	112
Accounts receivable, net	2,874	2,812
Inventories	821	756
Other	428	376
Total current assets	4,232	4,031
Property and equipment, net	8,078	7,871
Investments in and advances to affiliates	17	16
Goodwill and other intangible assets	1,703	1,705
Other	24	27
Total assets	14,054	13,650
Current liabilities:
Accounts payable	1,165	1,272
Accrued salaries	770	783
Other accrued expenses	540	517
Long-term debt due within one year	61	56
Total current liabilities	2,536	2,628
Long-term debt, net	222	185
Intercompany balances	(22,877)	(21,405)
Income taxes and other liabilities	428	605
Total liabilities	(19,691)	(17,987)
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	33,626	31,516
Noncontrolling interests	119	121
Total stockholders' deficit	33,745	31,637
Total liabilities and stockholders' deficit	14,054	13,650
Subsidiary Non-Guarantors [Member]
Current assets:
Cash and cash equivalents	479	479	$ 402	$ 302
Accounts receivable, net	2,953	2,882
Inventories	558	523
Other	574	531
Total current assets	4,564	4,415
Property and equipment, net	6,626	6,484
Investments of insurance subsidiaries	409	494
Investments in and advances to affiliates	169	149
Goodwill and other intangible assets	4,837	4,711
Other	187	158
Total assets	16,792	16,411
Current liabilities:
Accounts payable	703	762
Accrued salaries	588	587
Other accrued expenses	902	858
Long-term debt due within one year	52	51
Total current liabilities	2,245	2,258
Long-term debt, net	297	280
Intercompany balances	3,162	3,861
Professional liability risks	1,117	1,078
Income taxes and other liabilities	400	187
Total liabilities	7,221	7,664
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	8,208	7,472
Noncontrolling interests	1,363	1,275
Total stockholders' deficit	9,571	8,747
Total liabilities and stockholders' deficit	16,792	16,411
Eliminations [Member]
Current assets:
Investments in and advances to affiliates	(23,674)	(21,970)
Total assets	(23,674)	(21,970)
Current liabilities:
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(23,674)	(21,970)
Total stockholders' deficit	(23,674)	(21,970)
Total liabilities and stockholders' deficit	$ (23,674)	$ (21,970)