Property And Equipment, Net Property and Equipment, Net (Narrative) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) $ / Boe	Jun. 30, 2014 USD ($) $ / Boe	Jun. 30, 2015 USD ($) $ / Boe	Jun. 30, 2014 USD ($) $ / Boe
Property, Plant and Equipment [Abstract]
Average Depreciation Depletion And Amortization Per Boe | $ / Boe	23.81	26.34	23.63	26.49
Internal costs capitalized, Oil and Gas Producing Activities	$ 5.1	$ 5.3	$ 10.9	$ 10.7
Capitalized interest	$ 9.0	$ 8.6	$ 18.7	$ 16.3