Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Depreciation and fixed asset basis differences, Assets	$ 0	$ 0
Allowances for professional liability and other risks, Assets	403	365
Accounts receivable, Assets	341hca_DeferredTaxAssetsAccountsReceivable	423hca_DeferredTaxAssetsAccountsReceivable
Compensation, Assets	272	240
Other, Assets	756us-gaap_DeferredTaxAssetsOther	638us-gaap_DeferredTaxAssetsOther
Deferred tax assets	1,772us-gaap_DeferredTaxAssetsNet	1,666us-gaap_DeferredTaxAssetsNet
Depreciation and fixed asset basis differences, Liabilities	226	229
Allowances for professional liability and other risks, Liabilities	0	0
Accounts receivable, Liabilities	0	0
Compensation, Liabilities	0	0
Other, Liabilities	745us-gaap_DeferredTaxLiabilitiesOther	698us-gaap_DeferredTaxLiabilitiesOther
Deferred tax liabilities	$ 971us-gaap_DeferredTaxLiabilities	$ 927us-gaap_DeferredTaxLiabilities

Deferred tax assets, accounts receivable.

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- Definition

Deferred tax assets, allowances for professional liability and other risks.

+ References

No definition available.

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- Definition

Deferred tax liabilities accounts receivable.

+ References

No definition available.

+ Details

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- Definition

Deferred tax liabilities allowances for professional liability and other risks.

+ References

No definition available.

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- Definition

Deferred tax liabilities tax deferred expense compensation and benefits employee compensation.

+ References

No definition available.

+ Details

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- Definition

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b),(c)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 25

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=29652012&loc=d3e28680-109314

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from property, plant, and equipment.

+ References

No definition available.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 25

-Paragraph 20

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=29652012&loc=d3e28680-109314

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- Definition

Amount of deferred tax liability attributable to taxable temporary differences net of deferred tax asset attributable to deductible temporary differences and carryforwards after valuation allowances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32537-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=37586315&loc=d3e31931-109318

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- Definition

Amount of deferred tax liability attributable to taxable temporary differences not separately disclosed.

+ References

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- Definition

Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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