The cumulative cost of shares repurchased under a share repurchase program.

No definition available.

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- Definition

Cumulative number of shares that have been repurchased under a share repurchase program and are being held in treasury.

+ References

No definition available.

+ Details

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Data Type:	xbrli:sharesItemType
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Period Type:	instant

- Definition

Cumulative number of shares of common and preferred stock retired from treasury.

+ References

No definition available.

+ Details

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Namespace Prefix:	cog_
Data Type:	xbrli:sharesItemType
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- Details

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 30

-Article 5

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

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Balance Type:	na
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- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Period Type:	instant

- Definition

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.

+ References

+ Details

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Period Type:	duration

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28,29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

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- Details

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Period Type:

Capital Stock (Details) (USD $)	12 Months Ended
Capital Stock (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2014	May 30, 2014	May 01, 2014
Incentive Plans
Common stock, Authorized shares	960,000,000us-gaap_CommonStockSharesAuthorized	480,000,000us-gaap_CommonStockSharesAuthorized		960,000,000us-gaap_CommonStockSharesAuthorized	480,000,000us-gaap_CommonStockSharesAuthorized
Treasury stock
Number of shares repurchased	4,300,000us-gaap_TreasuryStockSharesAcquired	4,800,000us-gaap_TreasuryStockSharesAcquired	0us-gaap_TreasuryStockSharesAcquired
Cost of shares repurchased	$ 138,852,000	$ 164,634,000	$ 0
Cumulative number of shares repurchased under a share repurchase program	29,900,000
Treasury stock, number of shares authorized to be repurchased	40,000,000.0
Treasury stock, cumulative shares retired	20,000,000
Cumulative cost of shares repurchased under a share repurchase program	$ 388,400,000
Treasury stock reissued	0
Shares held as treasury stock	9,892,680us-gaap_TreasuryStockShares	5,618,166us-gaap_TreasuryStockShares
2014 Incentive Plan
Incentive Plans
Number of shares reserved for issuance						18,000,000
Number of shares available for issuance	18,000,000
2014 Incentive Plan \| Stock options \| Less than or equal to
Incentive Plans
Number of shares reserved for issuance						10,000,000