Restructuring and Impairment (Restructuring Activity) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 35	$ 51	$ 45
Restructuring payments	(32)	(34)	(34)
North America [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1	5	19	31
Restructuring payments	(3)	(6)	(13)
North America [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	(2)	(4)	(10)
North America [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	(1)	(2)	(3)
North America [Member] | Saguenay Plant Closure [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	5	0
North America [Member] | Saguenay Plant Closure [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	28
North America [Member] | Saguenay Plant Closure [Member] | Other Exit Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1	1	0	0
North America [Member] | Saguenay Plant Closure [Member] | Period Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	1	3	0
North America [Member] | Relocation of R&D Operations to Kennesaw, Georgia [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	1	8	3
North America [Member] | Relocation of R&D Operations to Kennesaw, Georgia [Member] | Period Expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	1	0	0
North America [Member] | Relocation of R&D Operations to Kennesaw, Georgia [Member] | Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	1	0	0
North America [Member] | Evermore Joint Venture Exit [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	1	0
North America [Member] | Evermore Joint Venture Exit [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	2	0
Europe [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3	27	11	49
Restructuring payments	(12)	(19)	(19)
Europe [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	(12)	(18)	(17)
Europe [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	0	(1)	(2)
Europe [Member] | Business Optimization [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3	26	10	6
Europe [Member] | Business Optimization [Member] | Pension Curtailment Loss [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	1	0	0
Europe [Member] | Rogerstone Plant Closure [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	18
Europe [Member] | Rogerstone Plant Closure [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	22
Europe [Member] | Rogerstone Plant Closure [Member] | Other Exit Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	1	3
South America [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	31	19	15	14
Restructuring payments	(16)	(8)	(2)
South America [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	(12)	(4)	(1)
South America [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring payments	(4)	(4)	(1)
South America [Member] | Non-core Assets [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	14	2	3	0
South America [Member] | Non-core Assets [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5	0	1	0
South America [Member] | Non-core Assets [Member] | Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5	1	5	0
South America [Member] | Non-core Assets [Member] | Environmental Remediation and Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6	16	0	0
South America [Member] | Aratu Plant Closure [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	7
South America [Member] | Aratu Plant Closure [Member] | Fixed Asset Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	0	7
South America [Member] | Aratu Plant Closure [Member] | Other Exit Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1	$ 0	$ 6	$ 0