Derivatives (Fair Value Of Derivative Instruments And Locations In Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Current derivative asset	$ 0	$ 0
Non-current derivative asset	0	377
Total derivatives assets	0	377
Current derivative liability	5,604	21,564
Non-current derivative liability	108	415
Total derivative liabilities	$ 5,712	$ 21,979