Compensation Plans (Details 2) (USD $)	3 Months Ended			3 Months Ended					3 Months Ended		1 Months Ended
	Mar. 31, 2014 award	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 APO Incentive Plan Minimum	Mar. 31, 2014 APO Incentive Plan Maximum	Mar. 31, 2014 APO Reward Plan area award	Mar. 31, 2014 APO Reward Plan Full vesting Date May 1, 2015 award	Mar. 31, 2014 APO Reward Plan Full vesting Date August 1, 2015 award	Mar. 31, 2014 APO Reward Plan Minimum	Mar. 31, 2014 APO Reward Plan Maximum	Jan. 31, 2007 SWR Reward Plan well
Non-Equity Award Plans
Subsequent revenues received by participants (as a percent)				99.00%	100.00%
Subsequent expenses paid by participants (as a percent)				99.00%	100.00%
Economic interests in specified wells drilled or acquired as part of the plan (as a percent)				5.00%	7.50%
Number of specified areas in which awards granted						12
Quarterly bonus amount, percentage of after-payout cash flow from wells drilled or recompleted, one						7.00%
Quarterly bonus amount, percentage of after-payout cash flow from wells drilled or recompleted, two						10.00%
Number of awards with specified vesting date						12	2	2
Number of awards vested	8
Percentage of working interest in well											22.50%
Number of wells, working interest											1
Percentage of subsequent quarterly bonus amounts after full vesting date payable to participants											100.00%
Vesting period									2 years	5 years
Compensation expense recorded	$ 4,700,000	$ 1,900,000
Current liabilities:
Accrued liabilities and other	3,458,000		3,317,000
Non-current liabilities:
Accrued compensation under non-equity award plans	18,752,000		15,469,000
Total accrued compensation under non-equity award plans	$ 22,210,000		$ 18,786,000