Transactions With Related Parties (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Sandhill Group LLC
Related Party Transaction [Line Items]
Due from related parties	$ 300		$ 300		$ 300
Revenue from Related Parties			1,488	$ 1,505
Poseidon Oil Pipeline Company
Related Party Transaction [Line Items]
Due from related parties	1,100		1,100		$ 1,900
Revenue from Related Parties	$ 1,980	$ 0	$ 3,956	$ 0