Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended		15 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jul. 01, 2012	Jul. 01, 2013	Sep. 30, 2012
Income Taxes [Line Items]
Effective income tax rate	23.70%	55.10%	(356.30%)	5.00%
Statutory rate		35.00%
Increase Decrease In Fair Value Of Equity Conversion Feature Of Preferred Stock	$ (52.6)	$ (81.9)	$ 124.0	$ 125.5
Valuation allowance, change in amount		49.3
Unrecognized tax benefits	9.0	9.0			5.9
Uncertain tax positions [Member]
Income Taxes [Line Items]
Accrued interest and penalties related to the uncertain tax positions	3.8	3.8			3.6
Reinsurance transaction [Member]
Income Taxes [Line Items]
Valuation allowance, change in amount			(19.0)	(19.0)
Contingent purchase price reduction receivable [Member]
Income Taxes [Line Items]
Valuation allowance, change in amount			41.0	41.0
Business acquisition [Member]
Income Taxes [Line Items]
Valuation allowance, change in amount			$ (13.9)