Equity-Based Compensation (CPE Inc. only) (Details 2) (Non-Qualified Stock Options, USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010 Y	Dec. 31, 2009 Y
Non-Qualified Stock Options
Share-based compensation plans
Award vesting period	3 years
Period within which share-based awards vest if employee is terminated without cause after change in control (in years)	2
Maximum exercise period of stock options (in years)	Ten years
Non-qualified stock option activity
Options outstanding at the beginning of the period (in shares)	1,032	1,012
Granted (in shares)	136	59
Forfeited (in shares)	(30)	(39)
Options outstanding at the end of the period (in shares)	1,138	1,032	1,012
Weighted Average Contractual Term (Years)
Options outstanding at the beginning of the period (in years)	8.91	9.89
Options outstanding at the end of the period (in years)	8.06	8.91	9.89
Aggregate Intrinsic Value	$ 4,240,000	$ 8,426,000
Weighted Average Exercise Price (per option)
Options outstanding at the beginning of the period (in dollars per share)	$ 15.07	$ 15.00
Granted (in dollars per share)	$ 20.99	$ 16.20
Forfeited (in dollars per share)	$ 15.54	$ 15.00
Options outstanding at the end of the period (in dollars per share)	$ 15.77	$ 15.07	$ 15.00
Assumptions used to estimate the fair value of options granted
Peer historical lookback period used for developing expected volatility (in years)	6.5
Weighted average fair value (per option)	$ 12.47	$ 9.34	$ 8.85
Assumptions:
Risk-free interest rate (as a percent)	2.90%	3.00%	2.90%
Expected option life	6.5	6.5	6.5
Expected volatility (as a percent)	59.50%	57.00%	59.00%
Unrecognized compensation cost	$ 3,900,000
Period over which unrecognized compensation cost is expected to be recognized (in years)	1