Earnings Per Common Share - Computation of EPS (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share Reconciliation [Abstract]
Net income	$ 4.5	$ 13.5	$ 17.1	$ 31.4
Preferred stock dividends	2.6	2.6	5.2	5.2
Net income applicable to common shareowners, basic	$ 1.9	$ 10.9	$ 11.9	$ 26.2
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average common shares outstanding - basic	195.8	198.0	195.5	197.9
Warrants	3.1	0.2	3.1	0.1
Stock-based compensation arrangements	2.8	2.8	3.1	2.7
Weighted average common shares outstanding - diluted	201.7	201.0	201.7	200.7
Basic earnings per common share	$ 0.01	$ 0.06	$ 0.06	$ 0.13
Diluted earnings per common share	$ 0.01	$ 0.05	$ 0.06	$ 0.13

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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