Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2012
Income Tax Disclosure [Line Items]
Income tax provisions associated with income from continuing operations	$ 1.9	$ 1.2
Effective tax rates	30.60%	36.00%
U.S. federal statutory tax rate	35.00%	35.00%
Income tax expense from discontinued operations		0.9
Income tax benefit from the sale of discontinued operations		0.6
Effective tax rate applied to discontinued operations		36.60%
Unrecognized tax benefits including interest and penalties	1.4		1.4
Liability for unrecognized tax benefits to change significantly in the next 12 months	$ 0