Earnings Per Common Share (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	3 Months Ended	12 Months Ended						12 Months Ended	3 Months Ended	12 Months Ended
	Oct. 29, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 0.875% Convertible Notes Due 2013 [Member]	Dec. 31, 2012 1.00% Senior Convertible Notes Due 2012 [Member]	Dec. 15, 2009 1.00% Senior Convertible Notes Due 2012 [Member]	Dec. 31, 2012 Subordinated Convertible Notes Due 2029 [Member]	Dec. 31, 2011 Common Stock [Member]	Dec. 31, 2012 Common Stock [Member]	Dec. 31, 2011 Common Stock [Member]
Debt Instrument [Line Items]
Stock repurchase program, authorized amount	$ 125
Repurchase of common shares, value			1.2	62.5						62.5	1.2
Repurchase of common shares, shares										2,500,000	50,000	2,529,000
Average price per share		$ 24.72	$ 24.80
Stock options and restricted stock units excluded from the earnings per common share			553,000	506,000	404,000
Total debt		$ 1,048.9	$ 1,450.1	$ 1,048.9		$ 355.0			$ 429.5
Weighted average conversion price per share						$ 50.36	$ 83.93		$ 36.75
Strike price of warrants, per share			$ 76.00
Interest rate						0.875%	1.00%	1.00%
Average stock considered as issuable under the treasury			0	600,000	0