Public Offering of Units and Certain Provisions of the Partnership Agreement (Incentive Distributions) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company Share of Partnership Income Loss	$ 27,600,000	$ 15,500,000	$ 6,400,000
Incentive Distribution, Distribution	6,390,000	4,489,000	2,372,000
Stock-based compensation attributable to CEI's restricted shares	(6,973,000)	(4,205,000)	(3,119,000)
General partner interest in net income (loss)	(2,138,000)	(818,000)	15,000
General partner interest in net loss	$ (2,721,000)	$ (534,000)	$ (732,000)