Derivative And Financial Instruments (Eagle Ford) (Details) - Eagle Ford - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Oil and natural gas production, 2016	95.00%
Oil and natural gas production, 2017	90.00%
Oil and natural gas production, 2018	85.00%
Oil and natural gas production, 2019	85.00%
Oil and natural gas production, 2020	80.00%
Fair value of derivative instruments	$ 6.4	$ 15.0