Capital Stock and Earnings Per Share (Details 1) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings (Loss) per Share (CPE Inc. only)
Common stock authorized	200,000,000				200,000,000				200,000,000	200,000,000
Par value	$ 0.01				$ 0.01				$ 0.01	$ 0.01
Preferred stock authorized	20,000,000								20,000,000
Perferred stock par value	$ 0.01								$ 0.01
Shares of preferred stock	0								0
Earnings Per Share, Basic [Abstract]
Net income (loss)	$ (156,196)	$ 8,873	$ (52,897)	$ (4,680)	$ 5,665	$ 91,069	$ (2,148)	$ (15,626)	$ (204,900)	$ 78,960	$ 51,971
Weighted-average shares outstanding									61,053,000	60,826,000	60,652,000
Basic earnings (loss) per share	$ (2.55)	$ 0.15	$ (0.87)	$ (0.08)	$ 0.09	$ 1.5	$ (0.04)	$ (0.26)	$ (3.36)	$ 1.3	$ 0.86
Earnings Per Share, Diluted [Abstract]
Net income (loss)	$ (156,196)	$ 8,873	$ (52,897)	$ (4,680)	$ 5,665	$ 91,069	$ (2,148)	$ (15,626)	$ (204,900)	$ 78,960	$ 51,971
Weighted-average shares outstanding									0	469,000	509,000
Denominator for diluted earnings (loss) per share									61,053,000	61,295,000	61,161,000
Diluted earnings per share (in dollars per share)	$ (2.55)	$ 0.14	$ (0.87)	$ (0.08)	$ 0.09	$ 1.49	$ (0.04)	$ (0.26)	$ (3.36)	$ 1.29	$ 0.85
LTIP
Earnings Per Share, Basic, Other Disclosures [Abstract]
Ant-dilutive stock equivalents									2,276,000	985,000	712,000