Segment, Major Customer and Major Supplier Information - Additional Information (Details)	3 Months Ended
	Sep. 30, 2025 country segement plant
Segment Reporting Information [Line Items]
Number of operating segments \| segement	4
Number of operating plants	29
Number of plants with recycling operations	15
Number of countries Company operates in \| country	9
Number of continents Company operates in \| segement	4
North America
Segment Reporting Information [Line Items]
Number of operating plants	13
Number of plants with recycling operations	7
Number of countries Company operates in \| country	2
Europe
Segment Reporting Information [Line Items]
Number of operating plants	10
Number of plants with recycling operations	5
Number of countries Company operates in \| country	4
Asia
Segment Reporting Information [Line Items]
Number of operating plants	4
Number of plants with recycling operations	2
Number of countries Company operates in \| country	2
South America
Segment Reporting Information [Line Items]
Number of operating plants	2
Number of plants with recycling operations	1
Number of countries Company operates in \| country	1

Novelis Inc. 10-Q