Impairment of Property and Equipment (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 method	Sep. 30, 2013
Property, Plant and Equipment Impairment or Disposal [Abstract]
Number of methods to determine fair value of impaired property			3
Impairment of property and equipment	$ 0	$ 709,000	$ 3,406,000	$ 89,811,000
Provisions for impairment of unproved properties	$ 900,000	$ 600,000	$ 5,900,000	$ 900,000