Acquisitions (Details 7) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($) item	Mar. 31, 2015 USD ($) item shares
Estimated fair values of the assets acquired and liabilities assumed
Goodwill	$ 1,451,654	$ 1,402,761
Change
Goodwill	1,973
Retail Propane
Acquisitions
Number of businesses acquired | item		8
Cash paid	$ 4,600	$ 39,000
Retail Propane - 2015 Acquisitions, seven completed acquisitions
Acquisitions
Number of business combinations for which acquisition accounting is completed | item	7
Estimated fair values of the assets acquired and liabilities assumed
Accounts receivable - trade	$ 1,913
Inventories	583
Prepaid expenses and other current assets	110
Goodwill	8,097
Accounts payable - trade	(1,523)
Advance payments received from customers	(1,661)
Current maturities of long-term debt	(78)
Long-term debt, net of current maturities	(760)
Fair value of net assets acquired	$ 38,647
Retail Propane 2015 Acquisitions, one in the process of completion
Acquisitions
Number of business combinations for which acquisition accounting remains to be completed | item	1
Estimated fair values of the assets acquired and liabilities assumed
Accounts receivable - trade	$ 324
Inventories	188
Advance payments received from customers	(87)
Fair value of net assets acquired	4,136
Change
Accounts payable - trade	398
Advance payments received from customers	2
Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Accounts receivable - trade		1,913
Inventories		583
Prepaid expenses and other current assets		110
Goodwill		8,097
Accounts payable - trade		(1,523)
Advance payments received from customers		(1,661)
Current maturities of long-term debt		(78)
Long-term debt, net of current maturities		(760)
Fair value of net assets acquired		38,647
Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Accounts receivable - trade		324
Inventories		188
Accounts payable - trade		(398)
Advance payments received from customers		(89)
Fair value of net assets acquired		4,136
Retail propane equipment | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	10,821
Retail propane equipment | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	2,356
Retail propane equipment | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		10,821
Retail propane equipment | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		2,356
Vehicles and railcars | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	1,953
Vehicles and railcars | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	379
Vehicles and railcars | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		1,953
Vehicles and railcars | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		379
Buildings and leasehold improvements | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	$ 534
Useful life of property, plant and equipment	30 years
Buildings and leasehold improvements | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	30 years
Change
Property, plant and equipment	$ (250)
Buildings and leasehold improvements | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		534
Buildings and leasehold improvements | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		250
Land | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	455
Land | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	50
Change
Property, plant and equipment	(150)
Land | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		455
Land | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		200
Other | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	90
Other | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment	$ 26
Other | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		90
Other | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Property, plant and equipment		26
Minimum | Retail propane equipment
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	2 years
Minimum | Retail propane equipment | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	15 years
Minimum | Retail propane equipment | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	15 years
Minimum | Vehicles and railcars
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	3 years
Minimum | Vehicles and railcars | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	5 years
Minimum | Vehicles and railcars | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	5 years
Minimum | Buildings and leasehold improvements
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	3 years
Minimum | Other | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	5 years
Minimum | Other | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	5 years
Maximum | Retail propane equipment
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	30 years
Maximum | Retail propane equipment | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	20 years
Maximum | Retail propane equipment | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	20 years
Maximum | Vehicles and railcars
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	25 years
Maximum | Vehicles and railcars | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	7 years
Maximum | Vehicles and railcars | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	7 years
Maximum | Buildings and leasehold improvements
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	40 years
Maximum | Other | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	7 years
Maximum | Other | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	7 years
Customer relationships | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets	$ 16,763
Customer relationships | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets	$ 800
Customer relationships | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets		16,763
Customer relationships | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets		800
Customer relationships | Minimum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	10 years
Customer relationships | Minimum | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	10 years
Customer relationships | Maximum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	15 years
Customer relationships | Maximum | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	15 years
Non-compete agreements | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets	$ 400
Non-compete agreements | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets	$ 100
Non-compete agreements | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets		400
Non-compete agreements | Estimated | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets		100
Non-compete agreements | Minimum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	5 years
Non-compete agreements | Minimum | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	5 years
Non-compete agreements | Maximum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	7 years
Non-compete agreements | Maximum | Retail Propane 2015 Acquisitions, one in the process of completion
Estimated fair values of the assets acquired and liabilities assumed
Useful life of property, plant and equipment	7 years
Trade names | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets	$ 950
Trade names | Estimated | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Intangible assets		$ 950
Trade names | Minimum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	3 years
Trade names | Maximum | Retail Propane - 2015 Acquisitions, seven completed acquisitions
Estimated fair values of the assets acquired and liabilities assumed
Useful life of intangible assets	12 years
Common Units | Retail Propane
Acquisitions
Common units issued | shares		132,100
Value of common units issued		$ 3,700