Fair Value Measurements - Significant Unobservable Inputs Used to Value Level 3 Instruments (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2024 $ / MWh $ / MMBTU	Sep. 30, 2024 USD ($) $ / MWh $ / MMBTU	Dec. 31, 2023 USD ($)
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets, Fair Value Disclosure		$ 1,692,670	$ 1,570,845
Level 3
Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments
Assets, Fair Value Disclosure		56	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, Fair Value Disclosure		56	6,616
Liabilities, Fair Value Disclosure		$ 18,144	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	37.79	116.60
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.00	0.06
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	259.04	155.13
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.08	0.11
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	158.08	136.61
Natural gas forward price (in usd per MMBTu) | $ / MMBTU	0.03	0.01
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 price volatilities		2.94
Natural gas price volatilities		1.01
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 price volatilities		3.77
Natural gas price volatilities		1.31
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 price volatilities		3.36
Natural gas price volatilities		1.18
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, Fair Value Disclosure		$ 0	6,587
Liabilities, Fair Value Disclosure		17,034	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, Fair Value Disclosure		0
Liabilities, Fair Value Disclosure		928
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, Fair Value Disclosure		56	29
Liabilities, Fair Value Disclosure		$ 182	$ 1,037