Significant Restructuring Costs - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended	12 Months Ended
	Mar. 31, 2013 Employees Plant	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2013 Employees Plant	Sep. 30, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 84	$ 245	$ 52	$ 84	$ 297
Number of employees to be severed	8,600
Number of employees severed	3,300			3,300
Plants to be closed	13			13
Plants closed	3			3
Automotive Experience
Restructuring Cost and Reserve [Line Items]
Number of employees to be severed	6,200
Plants to be closed	10			10
Building Efficiency
Restructuring Cost and Reserve [Line Items]
Number of employees to be severed	1,700
Plants to be closed	1			1
Power Solutions
Restructuring Cost and Reserve [Line Items]
Number of employees to be severed	700
Plants to be closed	2			2