Stanwell Liabilities (Narrative) (Details) T in Thousands, $ in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2026 AUD ($) T	Mar. 31, 2026 USD ($) T	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Aug. 14, 2018 AUD ($)	Aug. 14, 2018 USD ($)
Contract Obligations [Line Items]
Deferred consideration liability			$ 365,493	$ 346,768
Contract obligations			18,782	21,173
Stanwell Reserve Area Deferred Consideration [Member]
Contract Obligations [Line Items]
Deferred consideration liability					$ 210.0	$ 155,200
Contractual pre-tax discount rate	13.00%	13.00%
Stanwell Prepaid Coal Supply Liability [Member]
Contract Obligations [Line Items]
Non-market portion of coal leases \| T	800	800
Prepayment, discount period	5 years	5 years
Prepaid coal supply liability interest rate	13.00%	13.00%
Contract obligations	$ 250.7		171,600	155,027
Interest expense	$ 7.5	$ 5,200
Second Amendment Deed [Member]
Contract Obligations [Line Items]
Liquidity benchmark for prepayment settlement		$ 300,000
Prepayment and deferred payment balance interest rate	7.50%	7.50%
Accrued interest amount capped percent	120.00%	120.00%
Cash liquidity benchmark for distributions			300,000
Second Amendment Deed [Member] \| Minimum [Member]
Contract Obligations [Line Items]
Liquidity benchmark for prepayments		$ 200,000
Range of broader annual nominations \| T	1,200	1,200
Second Amendment Deed [Member] \| Maximum [Member]
Contract Obligations [Line Items]
Liquidity benchmark for prepayments		$ 250,000
Range of broader annual nominations \| T	2,240	2,240
Stanwell Prepayment And Deferred Payment [Member]
Contract Obligations [Line Items]
Contract obligations			25,830	$ 0
Cumulative rebate amount			$ 23,600
Change of control provision	2 years	2 years
Control of interest percent disposed to trigger payout in agreement	20.00%	20.00%