Fair Value of Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified																3 Months Ended		6 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2014 Cross-commodity bbl	Mar. 31, 2014 Cross-commodity bbl	Sep. 30, 2014 Crude oil fixed-price bbl	Mar. 31, 2014 Crude oil fixed-price bbl	Sep. 30, 2014 Crude oil index bbl	Mar. 31, 2014 Crude oil index bbl	Sep. 30, 2014 Propane fixed-price bbl	Mar. 31, 2014 Propane fixed-price bbl	Sep. 30, 2014 Refined products fixed-price bbl	Mar. 31, 2014 Refined products fixed-price bbl	Sep. 30, 2014 Renewable products bbl	Mar. 31, 2014 Renewable products bbl	Mar. 31, 2014 Other	Sep. 30, 2014 Commodity contracts	Sep. 30, 2013 Commodity contracts	Sep. 30, 2014 Commodity contracts	Sep. 30, 2013 Commodity contracts
Derivative contract information
Total Notional Units (Barrels)			(12,000)	140,000	(1,638,000)	(1,600,000)	2,195,000	3,598,000	1,238,000	60,000	(4,475,000)	732,000	(14,000)	106,000
Fair Value of Net Assets (Liabilities)	$ 56,363	$ 8,034	$ (1,283)	$ (1,876)	$ 9,380	$ (2,796)	$ 4,397	$ 6,099	$ 53	$ 1,753	$ 38,712	$ 560	$ 5,104	$ 4,084	$ 210
Net cash collateral held	(13,704)	456
Net fair value of commodity derivatives on condensed consolidated balance sheet	42,659	8,490
Net gains (losses) on derivatives																$ 55,981	$ (10,672)	$ 38,496	$ (17,881)