Derivatives and Other Financial Instruments - Schedule of Outstanding Quantities of Derivative Instruments (Detail) kt in Thousands, € in Millions, kr in Millions, R$ in Millions, $ in Millions, $ in Millions	Jun. 30, 2025 EUR (€) MWh kt	Jun. 30, 2025 NOK (kr) MWh kt	Jun. 30, 2025 BRL (R$) MWh kt	Jun. 30, 2025 AUD ($) MWh kt	Jun. 30, 2025 CAD ($) MWh kt	Jun. 30, 2024 EUR (€) MWh kt	Jun. 30, 2024 NOK (kr) MWh kt	Jun. 30, 2024 BRL (R$) MWh kt	Jun. 30, 2024 AUD ($) MWh kt	Jun. 30, 2024 CAD ($) MWh kt
Foreign Exchange Buy Forwards [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Liabilities	€ 176	kr 8	R$ 107	$ 821	$ 0	€ 61	kr 85	R$ 351	$ 0	$ 22
Foreign Exchange Buy Forwards Undesignated [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Liabilities	821					0
Foreign Exchange Sell Forwards Undesignated [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Liabilities	32					0
Foreign Exchange Sell Forwards [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Liabilities	€ 10					€ 16
Commodity Sell Forwards [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Outstanding quantities of derivative instruments | kt	575	575	575	575	575	80	80	80	80	80
Commodity Buy Forwards [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Outstanding quantities of derivative instruments | kt	160	160	160	160	160	133	133	133	133	133
Commodity Buy Forwards Natural Gas [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Outstanding energy derivative instruments | MWh	6	6	6	6	6	0	0	0	0	0
Commodity Buy Forwards Electricity [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Outstanding energy derivative instruments | MWh	6	6	6	6	6	0	0	0	0	0