Fair Value of Financial Instruments - Derivative Contract Positions (Details) bbl in Thousands, $ in Thousands	12 Months Ended
	Mar. 31, 2024 USD ($) bbl	Mar. 31, 2023 USD ($) bbl
Derivative contract information
Fair Value of Net Assets (Liabilities)	$ 13,976	$ 66,811
Net cash collateral provided (held)	3,349	(47,800)
Net commodity derivative (liability) asset	17,325	19,011
Fixed-price contract | Crude oil
Derivative contract information
Fair Value of Net Assets (Liabilities)	(3,000)	52,613
Fixed-price contract | Propane
Derivative contract information
Fair Value of Net Assets (Liabilities)	1,870	(4,047)
Fixed-price contract | Refined products
Derivative contract information
Fair Value of Net Assets (Liabilities)	518	4,468
Fixed-price contract | Butane
Derivative contract information
Fair Value of Net Assets (Liabilities)	$ (2,222)	$ 3,485
Fixed-price contract | Long | Crude oil
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl		1,069
Fixed-price contract | Long | Propane
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl	6,980
Fixed-price contract | Short | Crude oil
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl	(174)
Fixed-price contract | Short | Propane
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl		(320)
Fixed-price contract | Short | Refined products
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl	(244)	(429)
Fixed-price contract | Short | Butane
Derivative contract information
Net Long (Short) Notional Units (in barrels) | bbl	(982)	(830)
Interest rate swap
Derivative contract information
Fair Value of Net Assets (Liabilities)	$ 515
Interest rate swap notional amount	$ 200,000
Interest rate swap fixed interest rate	4.32%
Interest rate swap unrealized gain	$ 500
Other
Derivative contract information
Fair Value of Net Assets (Liabilities)	$ 16,295	$ 10,292