Fair Value Measurements - Significant Unobservable Inputs Used to Value Level 3 Instruments (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2023 USD ($) $ / MMBTU $ / MWh
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	$ 1,603,342	$ 1,570,845
Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	73	6,616
Commodity Contracts | Level 3 | Forward Contracts
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	73	6,616
Liabilities	$ 16,044	$ 1,695
Commodity Contracts | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	25.27	37.79
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.14	0.00
Commodity Contracts | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	247.22	259.04
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.02	0.08
Commodity Contracts | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Weighted-Average
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	135.29	158.08
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	(0.01)	0.03
Commodity Option | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Minimum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	42.75
Electricity price volatilities	1.54
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	2.08
Natural gas price volatilities	0.56
Commodity Option | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Maximum
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	103.25
Electricity price volatilities	2.85
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	4.83
Natural gas price volatilities	0.78
Commodity Option | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow | Weighted-Average
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Electricity forward price (in usd per MWh) | $ / MWh	66.67
Electricity price volatilities	2.03
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	3.11
Natural gas price volatilities	0.69
Electricity | Commodity Contracts | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	$ 73	$ 6,587
Liabilities	13,206	658
Electricity | Commodity Option | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	0
Liabilities	801
Natural Gas | Commodity Contracts | Level 3 | Forward Contracts | Valuation Technique, Discounted Cash Flow
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets	0	29
Liabilities	$ 2,037	$ 1,037