Earnings Per Common Share (Reconciliation Of The Numerator And Denominator Of Earnings (Loss) Per Common Share) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Earnings Per Share [Abstract]
Net income for basic EPS computation	$ 4.4	$ 3.6	$ 37.5	$ 38.2	$ 35.0	$ 18.1	$ 23.8	$ (7.8)	$ 83.8	[1]	$ 69.2	[1]	$ 56.3	[1]
Weighted average shares outstanding for basic EPS computation									51.9	[2],[3]	52.1	[2],[3]	52.0	[2],[3]
Earnings per common share - basic	$ 0.09	$ 0.07	$ 0.72	$ 0.73	$ 0.67	$ 0.35	$ 0.46	$ (0.15)	$ 1.61	[2]	$ 1.33	[2]	$ 1.08	[2]
Net income attributable to Company common shareholders	4.4	3.6	37.5	38.2	35.0	18.1	23.8	(7.8)	83.8	[1]	69.2	[1]	56.3	[1]
Add: preferred stock dividends, if applicable									0.3		0.3		0.3
Net income attributable to Company common shareholders — for diluted EPS computation	$ 4.5	$ 3.7	$ 37.6	$ 38.3	$ 35.1	$ 18.2	$ 23.9	$ (7.7)	$ 84.1	[1]	$ 69.5	[1]	$ 56.6	[1]
Weighted average shares outstanding including nonvested shares									51.9	[2],[3]	52.1	[2],[3]	52.0	[2],[3]
Dilutive effect of convertible notes									0.6		0		0
Dilutive effect of stock options and restricted stock units									0.8		0.6		0.4
Dilutive effect of assumed conversion of preferred stock									0.4		0.4		0.4
Weighted average shares outstanding for diluted EPS computation									53.7	[3]	53.1	[3]	52.8	[3]
Earnings per common share - assuming dilution	$ 0.09	$ 0.07	$ 0.68	$ 0.70	$ 0.66	$ 0.34	$ 0.45	$ (0.15)	$ 1.57		$ 1.31		$ 1.07

[1] Numerator

[2] Under the two class method, Earnings per share — basic reflects undistributed earnings per share for both common stock and unvested share-based payment awards (restricted stock).

[3] Denominator