Supplemental Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 673	$ 566	$ 658	$ 414
Accounts receivable, net	5,804	5,694
Inventories	1,348	1,279
Deferred income taxes	376	366
Other	1,092	1,025
Total current assets	9,293	8,930
Property and equipment, net	14,560	14,355
Investments of insurance subsidiaries	404	494
Investments in and advances to affiliates	182	165
Goodwill and other intangible assets	6,484	6,416
Other	787	620
Total assets	31,710	30,980
Current liabilities:
Accounts payable	1,884	2,035
Accrued salaries	1,282	1,370
Other accrued expenses	1,770	1,737
Long-term debt due within one year	1,374	338
Total current liabilities	6,310	5,480
Long-term debt, net	28,363	29,088
Professional liability risks	1,132	1,078
Income taxes and other liabilities	1,860	1,832
Total liabilities	37,665	37,478
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(7,406)	(7,894)
Noncontrolling interests	1,451	1,396
Total stockholders' deficit	(5,955)	(6,498)
Total liabilities and stockholders' deficit	31,710	30,980
HCA Holdings, Inc. Issuer [Member]
Current assets:
Deferred income taxes	376	366
Other	57	118
Total current assets	433	484
Investments in and advances to affiliates	23,262	21,970
Other	571	435
Total assets	24,266	22,889
Current liabilities:
Accounts payable	7	1
Other accrued expenses	29	45
Total current liabilities	36	46
Long-term debt, net	982	2,499
Intercompany balances	30,108	27,685
Income taxes and other liabilities	546	553
Total liabilities	31,672	30,783
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(7,406)	(7,894)
Total stockholders' deficit	(7,406)	(7,894)
Total liabilities and stockholders' deficit	24,266	22,889
HCA Inc. Issuer [Member]
Current liabilities:
Other accrued expenses	359	317
Long-term debt due within one year	1,264	231
Total current liabilities	1,623	548
Long-term debt, net	26,865	26,124
Intercompany balances	(11,233)	(10,141)
Income taxes and other liabilities	467	487
Total liabilities	17,722	17,018
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(17,722)	(17,018)
Total stockholders' deficit	(17,722)	(17,018)
Subsidiary Guarantors [Member]
Current assets:
Cash and cash equivalents	130	87	215	112
Accounts receivable, net	2,907	2,812
Inventories	807	756
Other	421	376
Total current assets	4,265	4,031
Property and equipment, net	7,968	7,871
Investments in and advances to affiliates	16	16
Goodwill and other intangible assets	1,704	1,705
Other	21	27
Total assets	13,974	13,650
Current liabilities:
Accounts payable	1,149	1,272
Accrued salaries	721	783
Other accrued expenses	507	517
Long-term debt due within one year	59	56
Total current liabilities	2,436	2,628
Long-term debt, net	225	185
Intercompany balances	(22,244)	(21,405)
Income taxes and other liabilities	459	605
Total liabilities	(19,124)	(17,987)
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	32,976	31,516
Noncontrolling interests	122	121
Total stockholders' deficit	33,098	31,637
Total liabilities and stockholders' deficit	13,974	13,650
Subsidiary Non-Guarantors [Member]
Current assets:
Cash and cash equivalents	543	479	$ 443	$ 302
Accounts receivable, net	2,897	2,882
Inventories	541	523
Other	614	531
Total current assets	4,595	4,415
Property and equipment, net	6,592	6,484
Investments of insurance subsidiaries	404	494
Investments in and advances to affiliates	166	149
Goodwill and other intangible assets	4,780	4,711
Other	195	158
Total assets	16,732	16,411
Current liabilities:
Accounts payable	728	762
Accrued salaries	561	587
Other accrued expenses	875	858
Long-term debt due within one year	51	51
Total current liabilities	2,215	2,258
Long-term debt, net	291	280
Intercompany balances	3,369	3,861
Professional liability risks	1,132	1,078
Income taxes and other liabilities	388	187
Total liabilities	7,395	7,664
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	8,008	7,472
Noncontrolling interests	1,329	1,275
Total stockholders' deficit	9,337	8,747
Total liabilities and stockholders' deficit	16,732	16,411
Eliminations [Member]
Current assets:
Investments in and advances to affiliates	(23,262)	(21,970)
Total assets	(23,262)	(21,970)
Current liabilities:
Stockholders' (deficit) equity attributable to HCA Holdings, Inc.	(23,262)	(21,970)
Total stockholders' deficit	(23,262)	(21,970)
Total liabilities and stockholders' deficit	$ (23,262)	$ (21,970)