Supplemental Condensed Consolidating Financial Information and Other Collateral-Related Information - Schedule of Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 868	$ 732
Accounts receivable	6,592	6,501
Inventories	1,636	1,573
Other	1,298	1,171
Total current assets	10,394	9,977
Property and equipment, net	18,544	17,895
Investments of insurance subsidiaries	414	418
Investments in and advances to affiliates	234	199
Goodwill and other intangible assets	7,459	7,394
Other	697	710
Total assets	37,742	36,593
Current liabilities:
Accounts payable	2,457	2,606
Accrued salaries	1,315	1,369
Other accrued expenses	2,161	1,983
Long-term debt due within one year	1,692	200
Total current liabilities	7,625	6,158
Long-term debt, net	31,500	32,858
Professional liability risks	1,283	1,198
Income taxes and other liabilities	1,459	1,374
Total liabilities	41,867	41,588
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	(5,989)	(6,806)
Noncontrolling interests	1,864	1,811
Total stockholders' deficit	(4,125)	(4,995)
Total liabilities and stockholders' deficit	37,742	36,593
HCA Healthcare, Inc. Issuer [Member]
Current assets:
Cash and cash equivalents		1
Total current assets		1
Investments in and advances to affiliates	31,540	29,581
Other	450	510
Total assets	31,990	30,092
Current liabilities:
Accounts payable	1
Other accrued expenses	101	29
Total current liabilities	102	29
Long-term debt, net	995	995
Intercompany balances	36,325	35,322
Income taxes and other liabilities	557	552
Total liabilities	37,979	36,898
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	(5,989)	(6,806)
Total stockholders' deficit	(5,989)	(6,806)
Total liabilities and stockholders' deficit	31,990	30,092
HCA Inc. Issuer [Member]
Current assets:
Other	98	50
Total assets	98	50
Current liabilities:
Other accrued expenses	382	378
Long-term debt due within one year	1,597	97
Total current liabilities	1,979	475
Long-term debt, net	30,048	31,367
Intercompany balances	(8,608)	(9,742)
Total liabilities	23,419	22,100
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	(23,321)	(22,050)
Total stockholders' deficit	(23,321)	(22,050)
Total liabilities and stockholders' deficit	98	50
Subsidiary Guarantors [Member]
Current assets:
Cash and cash equivalents	197	112
Accounts receivable	3,873	3,693
Inventories	1,093	1,030
Other	743	663
Total current assets	5,906	5,498
Property and equipment, net	11,842	11,110
Investments in and advances to affiliates	28	22
Goodwill and other intangible assets	5,429	4,893
Other	29	47
Total assets	23,234	21,570
Current liabilities:
Accounts payable	1,683	1,793
Accrued salaries	836	862
Other accrued expenses	670	536
Long-term debt due within one year	61	64
Total current liabilities	3,250	3,255
Long-term debt, net	282	307
Intercompany balances	(26,352)	(25,228)
Income taxes and other liabilities	388	357
Total liabilities	(22,432)	(21,309)
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	45,588	42,755
Noncontrolling interests	78	124
Total stockholders' deficit	45,666	42,879
Total liabilities and stockholders' deficit	23,234	21,570
Subsidiary Non-Guarantors [Member]
Current assets:
Cash and cash equivalents	671	619
Accounts receivable	2,719	2,808
Inventories	543	543
Other	555	508
Total current assets	4,488	4,478
Property and equipment, net	6,702	6,785
Investments of insurance subsidiaries	414	418
Investments in and advances to affiliates	206	177
Goodwill and other intangible assets	2,030	2,501
Other	120	103
Total assets	13,960	14,462
Current liabilities:
Accounts payable	773	813
Accrued salaries	479	507
Other accrued expenses	1,008	1,040
Long-term debt due within one year	34	39
Total current liabilities	2,294	2,399
Long-term debt, net	175	189
Intercompany balances	(1,365)	(352)
Professional liability risks	1,283	1,198
Income taxes and other liabilities	514	465
Total liabilities	2,901	3,899
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	9,273	8,876
Noncontrolling interests	1,786	1,687
Total stockholders' deficit	11,059	10,563
Total liabilities and stockholders' deficit	13,960	14,462
Eliminations [Member]
Current assets:
Investments in and advances to affiliates	(31,540)	(29,581)
Total assets	(31,540)	(29,581)
Current liabilities:
Stockholders' (deficit) equity attributable to HCA Healthcare, Inc.	(31,540)	(29,581)
Total stockholders' deficit	(31,540)	(29,581)
Total liabilities and stockholders' deficit	$ (31,540)	$ (29,581)