Noncontrolling Interests (Rollforward Redeemable Noncontrolling Interest) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Redeemable Noncontrolling Interest [Line Items]        
Balance, beginning of period $ 288.7 $ 358.7 $ 287.2 $ 375.8
Net income (loss) 0 0.7 5.4 2.0
Dividends 0 0 0 (3.5)
Currency translation adjustment (8.7) (15.8) (12.6) (30.7)
Balance, end of period $ 280.0 $ 343.6 $ 280.0 $ 343.6