Derivative Instruments and Hedging Activities - Outstanding commodity hedge contracts (Detail)	Mar. 31, 2016 T lb	Sep. 30, 2015 T lb	Mar. 31, 2015 T lb
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Pounds of Copper | lb	7,155,000	14,648,000	7,805,000
Metric Tons of Lead	4,595	6,785	10,952
Metric Tons of Aluminum	2,785	5,700	1,830
Metric Tons of Tin	688	2,080	1,000