Derivatives (Fair Value Of Derivative Instruments And Locations In Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Current derivative asset	$ 3,948	$ 0
Non-current derivative asset	689	377
Total derivatives assets	4,637	377
Current derivative liability	1,036	21,564
Non-current derivative liability	0	415
Total derivative liabilities	$ 1,036	$ 21,979