Consolidated Balance Sheets (Parenthetical) (Unaudited) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014
Statement of Financial Position [Abstract]
Valuation allowance for deferred income taxes	$ 30.9	$ 31.1
Preferred stock, par value	$ 0.1	$ 0.1
Preferred stock, shares authorized	30,000,000us-gaap_PreferredStockSharesAuthorized	30,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock, shares issued	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000us-gaap_CommonStockSharesAuthorized	1,000,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	373,741,449us-gaap_CommonStockSharesIssued	371,786,765us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	366,541,378us-gaap_CommonStockSharesOutstanding	364,586,694us-gaap_CommonStockSharesOutstanding
Treasury stock, shares	7,200,071us-gaap_TreasuryStockShares	7,200,071us-gaap_TreasuryStockShares

Face amount or stated value per share of common stock.

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