CONTRACT BALANCES - Hospital Operations and Other Segment (Details) - Hospital Operations and other - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Receivables
Balance at beginning of period	$ 171	$ 0
Increase/(decrease)	(19)	0
Balance at end of period	$ 152	$ 0
Contract assets, percentage to be reclassified to receivable within 90 days	89.00%

Change In Contract With Customer, Asset, Net, Current [Roll Forward]

No definition available.

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Namespace Prefix:	thc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contract With Customer, Asset, Net, Current, Period Increase (Decrease)

+ References

No definition available.

+ Details

Name:	thc_ContractWithCustomerAssetNetCurrentPeriodIncreaseDecrease
Namespace Prefix:	thc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Contract With Customer, Asset, Percentage To Be Reclassified To Receivable Within 90 Days

+ References

No definition available.

+ Details

Name:	thc_ContractWithCustomerAssetPercentageToBeReclassifiedToReceivableWithin90Days
Namespace Prefix:	thc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130533-203044

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Namespace Prefix:
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Balance Type:
Period Type: