Common Shares And Stock-Based Awards Plans (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			9 Months Ended	12 Months Ended	2 Months Ended	12 Months Ended
	Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009	Sep. 20, 2010 $100 Million Share Repurchase Program [Member]	Dec. 31, 2011 The 2010 Repurchase Program [Member]	Mar. 03, 2010 Maximum [Member] The 2010 Repurchase Program [Member]	Dec. 31, 2011 Stock Options [Member] years	Dec. 31, 2011 Employee Awards [Member] Stock Options [Member]	Dec. 31, 2011 Employee Awards [Member] Restricted Stock Units And Phantom Stock Awards [Member]	Dec. 31, 2011 Non-Employee Awards [Member] Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchase of common shares, value	$ 56.3	$ 58.9	$ 27.9		$ 35.1	$ 100.0
Repurchase of common shares	3,700,000	3,300,000	1,700,000	6,100,000
Repurchase of common shares, average price per share	$ 15.13	$ 17.70	$ 16.67
Vesting period, years								four	four	one
Contractual life of options							10
Non-employee director stock option plan, term in years	10
Additional shares available for issuance	4,400,000
Number of options, exercisable	3,730,000	3,600,000	3,100,000
Weighted-average exercise price of options exercisable	$ 20.32	$ 20.40	$ 19.97