Derivatives (Schedule of Effect on Operating Results) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Commodity Derivatives | Onshore facilities and transportation product costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (4,728)	$ 1,410	$ 9,083	$ (12,023)
Commodity Derivatives | Designated as Hedging Instrument | Onshore facilities and transportation product costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(3,399)	1,672	8,433	(8,279)
Commodity Derivatives | Not Designated As Hedging Instrument | Onshore facilities and transportation product costs
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(1,329)	(262)	650	(3,744)
Preferred Distribution Rate Reset Election | Other expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (2,276)	$ 0	$ (2,276)	$ 0