Income Taxes (Details 1) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended								12 Months Ended
	Apr. 02, 2012	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosures [Line Items]
Valuation allowance for deferred income taxes		$ 31.1				$ 31.0		$ 23.2		$ 31.1	$ 31.0
Valuation Allowance, Deferred Tax Asset, Change in Amount	753.2					(2.9)		18.7
Effective Income Tax Rate Reconciliation, Percent										34.50%	29.70%
Federal statutory rate										35.00%
Comparison of income tax expense (benefit) and tax computed at the statutory rate
Income taxes at federal statutory rate										285.0	230.2	85.0
Increase (decrease) in tax resulting from:
State income taxes, net of federal benefit										24.9	6.5	12.1
Domestic production activities deduction										(22.4)	(6.5)	0
Uncertain tax positions, net of deferred tax										(6.4)	(12.7)	(2.3)
Valuation allowance										0.1	(24.1)	(806.6)
Tax credits										(0.9)	(1.1)	(1.3)
Other										0.4	2.8	(0.3)
Total income tax expense (benefit)		84.5	58.7	70.9	66.5	63.3	59.1	31.1	41.6	280.7	195.1	(713.4)
ValuationAllowancePortionExpectedtobeWrittenOff [Member]
Income Tax Disclosures [Line Items]
Valuation allowance for deferred income taxes						13.2					13.2
Pro Forma [Member]
Income Tax Disclosures [Line Items]
Valuation allowance for deferred income taxes						7.1					7.1
Valuation Allowance, Deferred Tax Asset, Change in Amount												37.6
Increase (decrease) in tax resulting from:
Total income tax expense (benefit)											$ 6.0	$ 6.0