Commitments (Schedule Of Capital Leased Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Capital Leased Assets [Line Items]
Cost	$ 6,395	$ 6,345
Accumulated depreciation	(4,203)	(3,014)
Net book value	2,192	3,331
Computer Software and Equipment [Member]
Capital Leased Assets [Line Items]
Cost	6,080	6,081
Accumulated depreciation	(4,132)	(2,982)
Net book value	1,948	3,099
Yard Equipment [Member]
Capital Leased Assets [Line Items]
Cost	315	264
Accumulated depreciation	(71)	(32)
Net book value	$ 244	$ 232