Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Net sales	$ 2,831	$ 2,414	$ 5,511	$ 4,815
Cost of goods sold (exclusive of depreciation and amortization)	2,483	2,074	4,812	4,172
Selling, general and administrative expenses	103	109	211	229
Depreciation and amortization	90	79	179	156
Research and development expenses	12	12	24	22
Interest expense and amortization of debt issuance costs	82	75	163	151
Gain on assets held for sale	0	0	(11)	0
Restructuring and impairment, net	7	18	13	27
Equity in net loss of non–consolidated affiliates	0	3	2	7
Other expense (income), net	18	(5)	23	(15)
Total expenses	2,795	2,365	5,416	4,749
Income before income taxes	36	49	95	66
Income tax (benefit) provision	(2)	26	22	29
Net income	38	23	73	37
Net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to our common shareholder	$ 38	$ 23	$ 73	$ 37