Investments - Summary of Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Schedule of Equity Method Investments
Investments	$ 860,817	$ 660,778
White Cliffs
Schedule of Equity Method Investments
Investments	10,363	10,268
Advantage
Schedule of Equity Method Investments
Investments	72,651	76,834
Delaware Crossing
Schedule of Equity Method Investments
Investments	84,671	68,707
EPIC Y-Grade
Schedule of Equity Method Investments
Investments	163,244	162,850
EPIC Crude
Schedule of Equity Method Investments
Investments	362,912	339,116
EPIC Propane
Schedule of Equity Method Investments
Investments	7,028	3,003
Saddlehorn
Schedule of Equity Method Investments
Investments	$ 159,948	$ 0