CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Equity in earnings of NuStar Energy L.P.	$ 51,556	$ 56,096	$ 79,673
General and administrative expenses:
Third parties	(2,427)	(2,258)	(3,338)
Related party	(871)	(788)	0
Total general and administrative expenses	(3,298)	(3,046)	(3,338)
Other income (expense), net	41,942	3,021	(2,333)
Interest expense, net	(1,587)	(1,069)	(893)
Income before income tax (expense) benefit	88,613	55,002	73,109
Income tax (expense) benefit	(1,838)	66	(901)
Net income	86,775	55,068	72,208
Other comprehensive income (loss):
Share of NuStar Energy L.P.’s other comprehensive income (loss)	3,052	(685)	(3,107)
Pension and other postretirement benefit plan adjustments	0	(4,525)	218
Total other comprehensive income (loss)	3,052	(5,210)	(2,889)
Comprehensive income	$ 89,827	$ 49,858	$ 69,319
Net income per unit	$ 2.01	$ 1.28	$ 1.68
Weighted-average number of basic common units outstanding	42,954,230	42,932,320	42,914,297