Derivatives (Fair Value Of Derivative Instruments And Locations In Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Current derivative assets	$ 0	$ 10,186
Non-current derivative assets	377	968
Total derivatives assets	377	11,154
Current derivative liabilities	21,564	0
Non-current derivative liabilities	415	285
Total derivative liabilities	21,979	285
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Current derivative assets	0	10,186
Non-current derivative assets	377	968
Current derivative liabilities	21,564	0
Non-current derivative liabilities	$ 415	$ 285