Property, Plant And Equipment (Aging of Capitalized Exploratory Well Costs) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($) item	Jun. 30, 2014 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 122,075	$ 396,406	$ 120,455	$ 393,030
No. of Wells	10	32
No. of Projects	4	9
Zero to one year [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 217	$ 32,192
No. of Wells	2	2
No. of Projects	1	1
One to two years [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 32,192	$ 50,333
No. of Wells	2	3
No. of Projects	1	1
Two to three years [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 27,842	$ 37,969
No. of Wells	2	5
Three years or more [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Amount | $	$ 61,824	$ 275,912
No. of Wells	4	22
No. of Projects	2	7