Consolidation (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Mar. 31, 2013
Current assets
Cash and cash equivalents	$ 337	$ 509	$ 249	$ 301
Inventories	1,295	1,173
Prepaid expenses and other current assets	114	101
Total current assets	3,604	3,473
Property, plant and equipment, net	3,575	3,513
Goodwill	608	611
Deferred income taxes	80	80
Other long-term assets	183	173
Total assets	9,304	9,114
Current liabilities
Accounts payable	1,651	1,418
Accrued expenses and other current liabilities	455	547
Total current liabilities	3,297	3,170
Accrued postretirement benefits	632	621
Other long-term liabilities	269	271
Total liabilities	8,969	8,846
Logan [Member]
Current assets
Cash and cash equivalents	0	1
Accounts receivable - third parties	39	38
Inventories	45	42
Prepaid expenses and other current assets	1	1
Total current assets	85	82
Property, plant and equipment, net	11	14
Goodwill	12	12
Deferred income taxes	65	63
Other long-term assets	2	3
Total assets	175	174
Current liabilities
Accounts payable	25	26
Accrued expenses and other current liabilities	13	13
Total current liabilities	38	39
Accrued postretirement benefits	144	141
Other long-term liabilities	2	2
Total liabilities	$ 184	$ 182