SUPPLEMENTAL CASH FLOW & OTHER DATA (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Supplemental Cash Flow Elements [Abstract]
Depreciation expense	$ 57us-gaap_Depreciation	$ 53us-gaap_Depreciation
Amortization expense	21us-gaap_AmortizationOfIntangibleAssets	22us-gaap_AmortizationOfIntangibleAssets
Depreciation and amortization expense	78	75
Interest expense	45us-gaap_InterestExpense	40us-gaap_InterestExpense
Interest income	0	1
Interest expense, net	(45)us-gaap_InterestIncomeExpenseNet	(39)us-gaap_InterestIncomeExpenseNet
Interest paid	54us-gaap_InterestPaid	52us-gaap_InterestPaid
Income taxes paid	19us-gaap_IncomeTaxesPaid	9us-gaap_IncomeTaxesPaid
Assets acquired under capital leases	0us-gaap_CapitalLeaseObligationsIncurred	2us-gaap_CapitalLeaseObligationsIncurred
Accounts payable associated with capital expenditures	11	7
Fair value of assets acquired	0us-gaap_FairValueOfAssetsAcquired	646us-gaap_FairValueOfAssetsAcquired
Fair value of liabilities assumed	0us-gaap_LiabilitiesAssumed1	70us-gaap_LiabilitiesAssumed1
Fair value of net assets acquired	0dgx_FairValueOfNetAssetsAcquired	576dgx_FairValueOfNetAssetsAcquired
Less: Cash acquired	0us-gaap_CashAcquiredFromAcquisition	9us-gaap_CashAcquiredFromAcquisition
Business acquisitions, net of cash acquired	$ 0	$ 567

Fair value of net assets acquired

No definition available.

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- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Future cash outflow to pay for purchases of fixed assets that have occurred.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

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-Paragraph 5

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-SubTopic 10

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- Definition

The increase during the period in capital lease obligations due to entering into new capital leases.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

The cash inflow associated with the acquisition of business during the period (for example, cash that was held by the acquired business).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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-Paragraph 12

-Subparagraph (b)

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

+ Details

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- Definition

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

+ References

+ Details

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- Definition

The fair value of assets acquired in noncash investing or financing activities.

+ References

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.1-5)

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- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

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-Name Accounting Standards Codification

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-Subparagraph (SX 210.9-04.9)

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- Definition

The net amount of operating interest income (expense).

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

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- Definition

The amount of cash paid for interest during the period.

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- Definition

The fair value of liabilities assumed in noncash investing or financing activities.

+ References

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- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

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