Acquisitions (Details 4) (USD $)			6 Months Ended						0 Months Ended	6 Months Ended			6 Months Ended					6 Months Ended				6 Months Ended				6 Months Ended						6 Months Ended					6 Months Ended					6 Months Ended							6 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2014 Crude oil tanks and related equipment Minimum	Sep. 30, 2014 Crude oil tanks and related equipment Maximum	Sep. 30, 2014 Information technology equipment Minimum	Sep. 30, 2014 Information technology equipment Maximum	Sep. 30, 2014 Buildings and leasehold improvements Minimum	Sep. 30, 2014 Buildings and leasehold improvements Maximum	Dec. 02, 2013 Gavilon Energy	Sep. 30, 2014 Gavilon Energy	Mar. 31, 2014 Gavilon Energy Estimated	Sep. 30, 2014 Gavilon Energy Change	Sep. 30, 2014 Gavilon Energy Crude oil storage lease commitments	Dec. 02, 2013 Gavilon Energy Crude oil storage lease commitments	Sep. 30, 2014 Gavilon Energy Customer relationships	Mar. 31, 2014 Gavilon Energy Customer relationships Estimated	Sep. 30, 2014 Gavilon Energy Customer relationships Change	Sep. 30, 2014 Gavilon Energy Customer relationships Minimum	Sep. 30, 2014 Gavilon Energy Customer relationships Maximum	Sep. 30, 2014 Gavilon Energy Lease Agreements	Mar. 31, 2014 Gavilon Energy Lease Agreements Estimated	Sep. 30, 2014 Gavilon Energy Lease Agreements Minimum	Sep. 30, 2014 Gavilon Energy Lease Agreements Maximum	Sep. 30, 2014 Gavilon Energy Pipeline capacity rights	Sep. 30, 2014 Gavilon Energy Pipeline capacity rights Change	Sep. 30, 2014 Gavilon Energy Vehicles	Mar. 31, 2014 Gavilon Energy Vehicles Estimated	Sep. 30, 2014 Gavilon Energy Vehicles Change	Sep. 30, 2014 Gavilon Energy Crude oil tanks and related equipment	Mar. 31, 2014 Gavilon Energy Crude oil tanks and related equipment Estimated	Sep. 30, 2014 Gavilon Energy Crude oil tanks and related equipment Change	Sep. 30, 2014 Gavilon Energy Crude oil tanks and related equipment Minimum	Sep. 30, 2014 Gavilon Energy Crude oil tanks and related equipment Maximum	Sep. 30, 2014 Gavilon Energy Information technology equipment	Mar. 31, 2014 Gavilon Energy Information technology equipment Estimated	Sep. 30, 2014 Gavilon Energy Information technology equipment Change	Sep. 30, 2014 Gavilon Energy Information technology equipment Minimum	Sep. 30, 2014 Gavilon Energy Information technology equipment Maximum	Sep. 30, 2014 Gavilon Energy Buildings and leasehold improvements	Mar. 31, 2014 Gavilon Energy Buildings and leasehold improvements Estimated	Sep. 30, 2014 Gavilon Energy Buildings and leasehold improvements Change	Sep. 30, 2014 Gavilon Energy Buildings and leasehold improvements Minimum	Sep. 30, 2014 Gavilon Energy Buildings and leasehold improvements Maximum	Sep. 30, 2014 Gavilon Energy Land	Mar. 31, 2014 Gavilon Energy Land Estimated	Sep. 30, 2014 Gavilon Energy Tank bottoms	Mar. 31, 2014 Gavilon Energy Tank bottoms Estimated	Sep. 30, 2014 Gavilon Energy Tank bottoms Change	Sep. 30, 2014 Gavilon Energy Other	Mar. 31, 2014 Gavilon Energy Other Estimated	Sep. 30, 2014 Gavilon Energy Other Change	Sep. 30, 2014 Gavilon Energy Construction in progress	Mar. 31, 2014 Gavilon Energy Construction in progress Estimated	Sep. 30, 2014 Gavilon Energy Construction in progress Change	Dec. 31, 2013 Gavilon Energy Glass Mountain
Acquisitions
Cash paid, net of cash acquired									$ 832,400,000
Equity method ownership interest (as a percent)									11.00%																																														50.00%
Estimated fair values of the assets acquired and liabilities assumed
Accounts receivable - trade										326,484,000	349,529,000	(23,045,000)
Accounts receivable - affiliates										2,564,000	2,564,000
Inventories										107,430,000	107,430,000
Prepaid expenses and other current assets										68,322,000	68,322,000
Property, plant and equipment																										327,000	791,000	(464,000)	83,797,000	77,429,000	6,368,000			4,049,000	4,046,000	3,000			7,817,000	7,716,000	101,000			6,427,000	6,427,000	16,930,000	15,230,000	1,700,000	162,000	170,000	(8,000)	7,180,000	7,190,000	(10,000)
Useful life of property, plant and equipment			2 years	40 years	3 years	7 years	3 years	40 years																		3 years						3 years	40 years				3 years	7 years				3 years	40 years						7 years
Goodwill	1,170,490,000	1,107,006,000								342,769,000	359,169,000	(16,400,000)
Intangible assets															107,950,000	101,600,000	6,350,000			8,700,000	8,700,000			7,800,000	7,800,000
Useful life of intangible assets																		10 years	20 years			1 year	5 years
Investments in unconsolidated entities										183,000,000	178,000,000	5,000,000
Other noncurrent assets										2,287,000	9,918,000	(7,631,000)
Accounts payable - trade										(342,792,000)	(342,792,000)
Accounts payable - affiliates										(2,585,000)	(2,585,000)
Accrued expenses and other payables										(49,447,000)	(70,999,000)	(21,552,000)
Advance payments received from customers										(10,667,000)	(10,667,000)
Other noncurrent liabilities										(46,056,000)	(44,740,000)	(1,316,000)
Fair value of net assets acquired										832,448,000	832,448,000
Bonus expense recorded during the period										5,200,000
Additional bonus expense expected										1,600,000
Liability recorded in the acquisition accounting													15,900,000	13,900,000
Amortization of contract liabilities through cost of sales													5,000,000
Future amortization
2015 (six months)													3,670,000
2016													4,040,000
2017													$ 360,000