Earnings Per Common Share (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended									12 Months Ended
	Oct. 31, 2011	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2011 0.875% Convertible Notes Due 2013 [Member]	Dec. 31, 2011 1.00% Senior Convertible Notes Due 2012 [Member]	Dec. 15, 2009 1.00% Senior Convertible Notes Due 2012 [Member]	Dec. 31, 2011 Subordinated Convertible Notes Due 2029 [Member]
Debt Instrument [Line Items]
Stock repurchase program, authorized amount	$ 125
Repurchase of common shares		(62.5)	[1]	0	[1]	0	[1]
Stock repurchased		2,500,000
Average price per share		$ 24.72
Stock options and restricted stock units excluded from the earnings per common share		506,000		404,000		363,000
Total debt		$ 1,048.9		$ 985.5				$ 355.0	$ 10.6		$ 429.5
Weighted average conversion price per share								$ 50.36	$ 83.93		$ 36.75
Strike price of warrants, per share		$ 76.00						$ 76.00
Interest rate								0.875%	1.00%	1.00%
Average stock considered as issuable under the treasury		600,000		0		0

[1] See Note 22 -Restatement of Consolidated Financial Statements