Organization, Description of Business and Basis of Presentation (Narrative) (Details) $ in Thousands, bbl in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018 USD ($) Terminal bbl mi	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Terminal bbl mi	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Organization and Description of Business [Line Items]
Operating	$ 159,845		$ 145,294	$ 303,141	$ 276,886
General and administrative	53,290		43,393	99,846	83,674
Other (income) expense	(119)		$ 2,043	8,605	$ 3,213
Long-term pension and benefits	127,849			127,849		$ 111,305
Accumulated other comprehensive loss	$ 127,553			$ 127,553		$ 137,578
Refined Products Segment [Member]
Organization and Description of Business [Line Items]
Number of Pipeline Terminals | Terminal	53			53
Number of Independent Terminals | Terminal	26			26
Refined Products Segment [Member] | Refined Products Transportation Services [Member]
Organization and Description of Business [Line Items]
Pipeline Length | mi	9,700			9,700
Refined Products Segment [Member] | Ammonia Transportation Services [Member]
Organization and Description of Business [Line Items]
Pipeline Length | mi	1,100			1,100
Crude Oil Pipeline and Terminals Segment [Member]
Organization and Description of Business [Line Items]
Pipeline Length | mi	2,200			2,200
Storage Capacity | bbl	28			28
Contracted Storage | bbl	17			17
Marine Storage Segment [Member]
Organization and Description of Business [Line Items]
Number of Independent Terminals | Terminal	5			5
Storage Capacity | bbl	26			26
Error in Actuarial Assumptions [Member]
Organization and Description of Business [Line Items]
Net periodic benefit cost (credit)		$ 16,000
Operating		5,700
General and administrative		3,400
Other (income) expense		6,900
Long-term pension and benefits		18,800
Accumulated other comprehensive loss		$ 2,800