Accumulated Other Comprehensive Income (Loss) - AOCI Reclassifications (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net	$ (14)	$ (12)	$ (5)	$ (10)	$ (13)	$ (10)	$ (2)	$ (27)	$ (41)		$ (52)		$ (58)
Cost of goods sold	2,203	2,093	2,074	2,098	2,162	2,036	2,077	2,202	8,468		8,477		9,743
Net sales	2,549	2,403	2,414	2,401	2,500	2,321	2,441	2,550	9,767		9,812		11,063
SG&A	117	115	109	120	93	101	102	102	461		398		383
Income before income taxes									115		286		129
Income tax (provision) benefit	15	3	(26)	(3)	(14)	(11)	(37)	(21)	(11)		(83)		(39)
Net income	54	13	23	14	59	3	50	91	104		203		90
Cash Flow Hedging [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Income before income taxes									41		8		(13)
Income tax (provision) benefit									(16)		(2)		7
Net income									25		6		(6)
Cash Flow Hedging [Member] | Aluminium Contracts [Member] | Cost of Goods Sold [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									53	[1]	19	[1]	(16)	[1]
Cash Flow Hedging [Member] | Aluminium Contracts [Member] | Net Sales [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net sales									7		12		5
Cash Flow Hedging [Member] | Currency Exchange Contracts [Member] | Other Income, Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other income, net									(2)		(1)		(1)
Cash Flow Hedging [Member] | Currency Exchange Contracts [Member] | Cost of Goods Sold [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of goods sold									(14)	[1]	(15)	[1]	6	[1]
Cash Flow Hedging [Member] | Currency Exchange Contracts [Member] | Net Sales [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net sales									3		0		(3)
Cash Flow Hedging [Member] | Currency Exchange Contracts [Member] | SG&A [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
SG&A									$ (1)		$ (2)		$ 1

[1] "Cost of goods sold" is exclusive of depreciation and amortization.