Investments - Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	$ 5,409	$ (2,341)
White Cliffs
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	(715)	(1,048)
Advantage Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	(2,076)	(2,241)
Delaware Crossing Joint Venture
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	720	1,183
Saddlehorn
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	(4,626)	0
EPIC Propane
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	25	0
EPIC Y-Grade
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	5,618	30
EPIC Crude
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	6,901	0
Other
Schedule of Equity Method Investments [Line Items]
Total Investment Loss (Income)	$ (438)	$ (265)