Restructuring and Impairment (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Sep. 30, 2014		Mar. 31, 2014		Mar. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 13
Cash payments	(11)
Foreign currency translation and other	2
North America [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1		5		47
Cash payments	(1)		(6)
North America [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	0		(4)
North America [Member] | Severance [Member] | Saguenay Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0		5
North America [Member] | Severance [Member] | Relocation of Research and Development Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		1		11
North America [Member] | Fixed Asset Impairment [Member] | Saguenay Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	0	[1]	28	[1]
North America [Member] | Other Exit Related Costs [Member] | Saguenay Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1		1		0
North America [Member] | Period Expenses [Member] | Saguenay Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	1	[1]	3	[1]
North America [Member] | Period Expenses [Member] | Relocation of Research and Development Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	1	[1]	0	[1]
North America [Member] | Relocation Costs [Member] | Relocation of Research and Development Operations [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		1		0
North America [Member] | Other [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	(1)		(2)
Europe [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4		27		16
Cash payments	(9)		(19)
Foreign currency translation and other	(1)		0
Europe [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	(9)		(18)
Foreign currency translation and other	(1)		0
Europe [Member] | Severance [Member] | Business Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4		26		16
Europe [Member] | Other [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	0		(1)
Europe [Member] | Pension Settlement Loss [Member] | Business Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	1	[1]	0	[1]
South America [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8		19		29
Cash payments	(1)		(8)
Foreign currency translation and other	(1)		0
South America [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	0		(4)
South America [Member] | Severance [Member] | Non-core Assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		2		3
South America [Member] | Severance [Member] | Aratu Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0		7
South America [Member] | Fixed Asset Impairment [Member] | Non-core Assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	0	[1]	1	[1]
South America [Member] | Fixed Asset Impairment [Member] | Aratu Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	[1]	0	[1]	7	[1]
South America [Member] | Other Exit Related Costs [Member] | Aratu Plant Closure [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1		0		6
South America [Member] | Other [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	(1)		(4)
Foreign currency translation and other	(1)		0
South America [Member] | Contract Termination and Other [Member] | Non-core Assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1		1		5
South America [Member] | Environmental Charges [Member] | Non-core Assets [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6		16		0
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	0		(1)
Corporate [Member] | Relocation of Headquarters [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0		0		5
Corporate [Member] | Other [Member]
Restructuring Cost and Reserve [Line Items]
Cash payments	$ 0		$ (1)

[1] These charges were not recorded through the restructuring liability.