Restructuring Costs (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Sep. 30, 2014
Restructuring Reserve [Roll Forward]          
Beginning balance     $ 11 $ 12  
Charges to continuing operations 3 2 [1] 6 3  
Cash payments – continuing operations     (3) (4)  
Other     (2) (1)  
Total restructuring reserves 12 10 12 10  
Less: non-current restructuring reserves (2) (3) (2) (3) (2)
Restructuring reserves – current 10 7 10 7 9
Employee Termination Benefits          
Restructuring Reserve [Roll Forward]          
Beginning balance     11 12  
Charges to continuing operations     6 3  
Cash payments – continuing operations     (3) (4)  
Other     (2) (1)  
Total restructuring reserves 12 10 12 10  
Less: non-current restructuring reserves (2) (3) (2) (3)  
Restructuring reserves – current 10 7 10 7  
Asset Impairment          
Restructuring Reserve [Roll Forward]          
Beginning balance     0 0  
Charges to continuing operations     0 0  
Cash payments – continuing operations     0 0  
Other     0    
Total restructuring reserves 0 0 0 0  
Less: non-current restructuring reserves 0 0 0 0  
Restructuring reserves – current 0 0 0 0  
Plant Shutdown & Other          
Restructuring Reserve [Roll Forward]          
Beginning balance     0 0  
Charges to continuing operations     0 0  
Cash payments – continuing operations     0 0  
Other     0 0  
Total restructuring reserves 0 0 0 0  
Less: non-current restructuring reserves 0 0 0 0  
Restructuring reserves – current $ 0 $ 0 $ 0 $ 0  
[1] Amounts for prior periods have been recast for discontinued operations.