EARNINGS PER SHARE (Details) - Earnings Per Share (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013
Net income available to common shares	$ 25.7		$ 78.2		$ 105.0		$ 143.5
Basic weighted average shares outstanding (in shares)	247,700,000		263,600,000		250,200,000		264,700,000
Dilutive effect of non-participating share-based awards	900,000		2,000,000		1,700,000		2,000,000
Diluted weighted average common shares outstanding (in shares)	248,600,000		265,600,000		251,900,000		266,700,000
Basic EPS	$ 0.10		$ 0.30		$ 0.42		$ 0.54
Diluted EPS	$ 0.10		$ 0.29		$ 0.42		$ 0.54
Weighted average shares excluded from diluted EPS because the effect would be anti-dilutive [Line Item]
Shares Repurchased including net shares, total	3,400,000		4,400,000		12,200,000		7,100,000
Shares Repurchased including net shares average price per share	$ 17.21		$ 17.02		$ 17.26		$ 15.61
Shares Repurchased Including Net shares Aggregate Payment	0.3		75.1		211.3		75.1
Remaining Authorization	$ 209.7				$ 209.7
Net Shares Tendered By Employees	16,600	[1]	5,500	[1]	627,600	[1]	250,500	[1]
Share Based Awards [Member]
Weighted average shares excluded from diluted EPS because the effect would be anti-dilutive [Line Item]
Weighted average shares excluded from diluted EPS	6,100,000		8,500,000		4,700,000		8,900,000
Notes [Member]
Weighted average shares excluded from diluted EPS because the effect would be anti-dilutive [Line Item]
Weighted average shares excluded from diluted EPS	42,600,000		42,600,000		42,600,000		42,600,000
Note Hedges [Member]
Weighted average shares excluded from diluted EPS because the effect would be anti-dilutive [Line Item]
Weighted average shares excluded from diluted EPS	(42,600,000)		(42,600,000)		(42,600,000)		(42,600,000)
Warrant [Member]
Weighted average shares excluded from diluted EPS because the effect would be anti-dilutive [Line Item]
Weighted average shares excluded from diluted EPS	42,600,000		42,600,000		42,600,000		42,600,000

[1] Net shares tendered by employees at vesting for tax withholding obligations (in thousands)