Supplemental Oil and Gas Reserve Information (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flow Relating to Proved Oil and Gas Reserves [Roll Forward]
Standardized measure, beginning of period	$ 926,923	$ 939,831	$ 938,513
Net changes in sales prices, net of production costs	(94,104)	13,292	(196,930)
Revisions of quantity estimates	(234,612)	(10,680)	(144,899)
Accretion of discount	138,095us-gaap_AccretionOfDiscount	130,736us-gaap_AccretionOfDiscount	137,369us-gaap_AccretionOfDiscount
Changes in future development costs, including development costs incurred that reduced future development costs	146,392	46,068	148,733
Changes in timing and other	(70,774)cwei_ChangesInTimingAndOther	(10,249)cwei_ChangesInTimingAndOther	(58,323)cwei_ChangesInTimingAndOther
Net change in income taxes	2,893	(84,673)	76,593
Future abandonment cost, net of salvage	4,066cwei_FutureAbandonmentCostNetOfSalvage	232cwei_FutureAbandonmentCostNetOfSalvage	(9,230)cwei_FutureAbandonmentCostNetOfSalvage
Extensions and discoveries	431,895	502,619	289,999
Sales, net of production costs	(309,758)	(289,035)	(277,248)
Purchases of minerals-in-place	0	0	80,744
Sales of minerals-in-place	(8,103)	(311,218)	(45,490)
Standardized measure, end of period	$ 932,913	$ 926,923	$ 939,831

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

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-Name Accounting Standards Codification

-Topic 932

-SubTopic 235

-Section 50

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in the estimated future income tax on future pretax net cash flows related to the entity's proved oil and gas reserves.

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Amount of increase in standardized measure of discounted future net cash flow as a result of purchases of minerals in place.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of change in sales and transfer prices and in production (lifting) costs related to future production.

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Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of revisions of estimated quantity of oil and gas in proved reserves.

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Amount of standardized measure of discounted future net cash flow relating to proved oil and gas reserves.

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

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