Segment, Major Customer and Major Supplier Information - Net Sales by Value Stream (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Net sales	$ 3,935	$ 4,201	$ 12,133	$ 14,089
Beverage packaging
Segment Reporting Information [Line Items]
Net sales	1,909	1,998	5,636	6,800
Automotive
Segment Reporting Information [Line Items]
Net sales	892	934	2,881	2,876
Aerospace and industrial plate
Segment Reporting Information [Line Items]
Net sales	164	180	519	543
Specialty
Segment Reporting Information [Line Items]
Net sales	$ 970	$ 1,089	$ 3,097	$ 3,870