Basis for Presentation (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 item	Mar. 31, 2012
Revenue recognition
Number of estimates, a change in which could have material effect on financial position or results of operations			1
Number of transportation systems service contracts, which contain annual system usage incentives			1
Net Income Per Share
Dilutive shares (in shares)	26,736,000	26,736,000	26,736,000	26,736,000
Performance-based RSUs
Net Income Per Share
Dilutive shares (in shares)			0
Restricted stock units
Net Income Per Share
Dilutive shares (in shares)	0		0