Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2017
Property, Plant and Equipment
Gross property, plant and equipment	$ 2,128,857		$ 2,128,857		$ 2,165,867
Accumulated depreciation	(420,174)		(420,174)		(375,594)
Net property, plant and equipment	1,708,683		1,708,683		1,790,273
Depreciation expense	32,629	$ 32,039	98,761	$ 88,396
Capitalized interest expense	66	$ 1,429	66	$ 6,233
Gain (loss) on sales and write-downs of certain assets	(4,700)		(4,000)
Property, plant and equipment disposals	7,500		10,600
Natural gas liquids terminal and storage assets
Property, Plant and Equipment
Gross property, plant and equipment	238,092		$ 238,092		207,825
Natural gas liquids terminal and storage assets | Minimum
Property, Plant and Equipment
Useful life			2 years
Natural gas liquids terminal and storage assets | Maximum
Property, Plant and Equipment
Useful life			30 years
Pipeline and related facilities
Property, Plant and Equipment
Gross property, plant and equipment	255,930		$ 255,930		248,582
Pipeline and related facilities | Minimum
Property, Plant and Equipment
Useful life			30 years
Pipeline and related facilities | Maximum
Property, Plant and Equipment
Useful life			40 years
Refined products terminal assets and equipment
Property, Plant and Equipment
Gross property, plant and equipment	7,062		$ 7,062		6,736
Refined products terminal assets and equipment | Minimum
Property, Plant and Equipment
Useful life			15 years
Refined products terminal assets and equipment | Maximum
Property, Plant and Equipment
Useful life			25 years
Retail propane equipment
Property, Plant and Equipment
Gross property, plant and equipment	195,414		$ 195,414		239,417
Retail propane equipment | Minimum
Property, Plant and Equipment
Useful life			2 years
Retail propane equipment | Maximum
Property, Plant and Equipment
Useful life			30 years
Vehicles and railcars
Property, Plant and Equipment
Gross property, plant and equipment	179,691		$ 179,691		198,480
Vehicles and railcars | Minimum
Property, Plant and Equipment
Useful life			3 years
Vehicles and railcars | Maximum
Property, Plant and Equipment
Useful life			25 years
Water treatment facilities and equipment
Property, Plant and Equipment
Gross property, plant and equipment	585,569		$ 585,569		557,100
Water treatment facilities and equipment | Minimum
Property, Plant and Equipment
Useful life			3 years
Water treatment facilities and equipment | Maximum
Property, Plant and Equipment
Useful life			30 years
Crude oil tanks and related equipment
Property, Plant and Equipment
Gross property, plant and equipment	218,056		$ 218,056		203,003
Crude oil tanks and related equipment | Minimum
Property, Plant and Equipment
Useful life			2 years
Crude oil tanks and related equipment | Maximum
Property, Plant and Equipment
Useful life			30 years
Barges and towboats
Property, Plant and Equipment
Gross property, plant and equipment	91,884		$ 91,884		91,037
Barges and towboats | Minimum
Property, Plant and Equipment
Useful life			5 years
Barges and towboats | Maximum
Property, Plant and Equipment
Useful life			30 years
Information technology equipment
Property, Plant and Equipment
Gross property, plant and equipment	43,495		$ 43,495		43,880
Information technology equipment | Minimum
Property, Plant and Equipment
Useful life			3 years
Information technology equipment | Maximum
Property, Plant and Equipment
Useful life			7 years
Buildings and leasehold improvements
Property, Plant and Equipment
Gross property, plant and equipment	167,446		$ 167,446		161,957
Buildings and leasehold improvements | Minimum
Property, Plant and Equipment
Useful life			3 years
Buildings and leasehold improvements | Maximum
Property, Plant and Equipment
Useful life			40 years
Land
Property, Plant and Equipment
Gross property, plant and equipment	56,593		$ 56,593		56,545
Tank bottoms and line fill
Property, Plant and Equipment
Gross property, plant and equipment	20,094		20,094		24,462
Other
Property, Plant and Equipment
Gross property, plant and equipment	14,802		$ 14,802		39,132
Other | Minimum
Property, Plant and Equipment
Useful life			3 years
Other | Maximum
Property, Plant and Equipment
Useful life			20 years
Construction in progress
Property, Plant and Equipment
Gross property, plant and equipment	54,729		$ 54,729		$ 87,711
Crude oil logistics
Property, Plant and Equipment
Gain (loss) on sales and write-downs of certain assets	$ 2,800		$ 6,600