Earnings Per Common Share - Computation of EPS (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share Reconciliation [Abstract]
Net income	$ 3.9	$ 17.6	$ 21.0	$ 49.0
Preferred stock dividends	2.6	2.6	7.8	7.8
Net income applicable to common shareownders, basic	1.3	15.0	13.2	41.2
Net income applicable to common shareowners, diluted	$ 1.3	$ 15.0	$ 13.2	$ 41.2
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average common shares outstanding - basic	196.4	196.5	195.8	197.4
Warrants	5.6	1.2	3.9	0.5
Stock-based compensation arrangements	3.6	2.9	3.3	2.5
Weighted average common shares outstanding - diluted	205.6	200.6	203.0	200.4
Basic earnings per common share	$ 0.01	$ 0.08	$ 0.07	$ 0.21
Diluted earnings per common share	$ 0.01	$ 0.07	$ 0.07	$ 0.21