Revision To Previously Reported Financial Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006
Revision To Previously Reported Financial Information [Abstract]
Number of employees participating in program	82
Decrease in net income		$ 4.1	$ 5.9	$ 3.2	$ 2.0	$ 1.6	$ 0.5