Decommissioning and Other Asset Retirement Obligations (Details) (USD $)	3 Months Ended	6 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
Decommissioning and Other Asset Retirement Obligations Detail [Table]
Beginning balance for the period, as reported	$ 42,188,000	$ 50,904,000
Activity in the period:
Accretion of liability	199,000	570,000
Revisions in estimated cash flows	22,942,000	43,622,000
Settlement of retirement obligations	(10,542,000)	(40,309,000)
Ending balance as of June 30	54,787,000	42,188,000
Fair value of asset retirement obligations associated with non-operated properties	$ 8,300,000		$ 7,600,000