Earnings Per Share (Narrative) (Details) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Earnings Per Share [Abstract]
Weighted average unvested shares outstanding	0.3	0.2	0.2
Anti-dilutive stock options excluded from dilutive earnings per share calculation	0.1	0.2	0.6
Cumulative convertible preferred share, dividend rate	5.417%	5.417%	5.417%