Original dividend payable per share prior to cash dividend increase.

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Treasury Stock Acquired Accelerated Share Repurchase Final Shares

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Treasury stock acquired accelerated share repurchase, total cost

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Value of shares repurchase program authorized by Quest Diagnostic's Board of Directors

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Final price paid per share for the purchase of the targeted number of shares, determined by an average market price over a fixed period of time.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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The per share amount of a dividend declared, but not paid, as of the financial reporting date.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Number of treasury shares (units) reissued during the period, excluding reissuance of shares (units) held in treasury used to satisfy equity-based compensation obligations exercised by the holders of such rights. Upon reissuance of shares (units) from treasury, either the common or preferred stock (unit) reissued is outstanding.

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Amount remaining of a stock repurchase plan authorized by an entity's Board of Directors.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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PREFERRED STOCK AND COMMON STOCKHOLDERS' EQUITY (Narrative) (Details) (USD $)	1 Months Ended			12 Months Ended			0 Months Ended	1 Months Ended	3 Months Ended
	Aug. 31, 2013	Nov. 30, 2012	Jan. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 29, 2015	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	May 04, 2006	May 03, 2006
Schedule of Shareholders' Equity [Line Items]
Preferred stock, par value				$ 1.00
Preferred stock, shares outstanding				0us-gaap_PreferredStockSharesOutstanding
Common stock, par value				$ 0.01	$ 0.01												$ 0.01
Common stock, shares authorized				600,000,000us-gaap_CommonStockSharesAuthorized	600,000,000us-gaap_CommonStockSharesAuthorized												600,000,000us-gaap_CommonStockSharesAuthorized	300,000,000us-gaap_CommonStockSharesAuthorized
Dividend program				$ 0.33us-gaap_DividendsPayableAmountPerShare	$ 0.30us-gaap_DividendsPayableAmountPerShare	$ 0.30us-gaap_DividendsPayableAmountPerShare		$ 0.30us-gaap_DividendsPayableAmountPerShare	$ 0.30us-gaap_DividendsPayableAmountPerShare	$ 0.33us-gaap_DividendsPayableAmountPerShare	$ 0.33us-gaap_DividendsPayableAmountPerShare	$ 0.33us-gaap_DividendsPayableAmountPerShare	$ 0.30us-gaap_DividendsPayableAmountPerShare	$ 0.17us-gaap_DividendsPayableAmountPerShare	$ 0.17us-gaap_DividendsPayableAmountPerShare	$ 0.17us-gaap_DividendsPayableAmountPerShare
Original dividend payable per share		$ 0.17dgx_OriginalDividendPayablePerShare
Treasury stock value acquired cost method				$ 132,000,000	$ 1,037,000,000	$ 200,000,000
Stock repurchase program, remaining authorized repurchase amount	1,300,000,000		1,100,000,000	696,000,000
Reissuance of shares for employee benefit plan				2,000,000	3,000,000	4,000,000
Treasury stock aquired repurchase program	1,000,000,000		1,000,000,000
Maximum [Member]
Schedule of Shareholders' Equity [Line Items]
Preferred stock, shares authorized				10,000,000
Subsequent Event [Member]
Schedule of Shareholders' Equity [Line Items]
Dividend program							$ 0.38
Original dividend payable per share							$ 0.33
Accelerated Share Repurchase Program [Member]
Schedule of Shareholders' Equity [Line Items]
Treasury stock acquired accelerated share repurchase total cost								350,000,000	450,000,000
Treasury Stock Acquired Accelerated Share Repurchase Final Shares								5,800,000	7,600,000
Treasury stock acquired accelerated share repurchase, final purchase price, per share								$ 60.73	$ 59.46
Share Repurchases Open Market [Member]
Schedule of Shareholders' Equity [Line Items]
Treasury stock acquired average cost per share				$ 59.49	$ 57.63	$ 58.31
Treasury stock value acquired cost method				$ 132,000,000	$ 237,000,000	$ 200,000,000
Purchases of treasury stock, shares				2,200,000	4,100,000	3,400,000