Share-Based Compensation Plans - Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended					12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013 Employees Deferred Compensation Plan [Member]	Dec. 31, 2012 Employees Deferred Compensation Plan [Member]	Dec. 31, 2013 Non-employee Directors Deferred Compensation Plan [Member]	Dec. 31, 2012 Non-employee Directors Deferred Compensation Plan [Member]	Dec. 31, 2013 Performance Shares PSU [Member]	Dec. 31, 2013 Market Share Units MSU [Member]	Dec. 31, 2013 Restricted Stock Units RSU [Member]
Other Share-Based Compensation [Line Items]
Unrecognized compensation cost related to previously granted nonvested shares						$ 3.8	$ 0.8	$ 4.4
Unrecognized compensation cost related to previously granted nonvested shares period for recognition						1 year 9 months 18 days	0 years 0 months 12 days	1 year 8 months 6 days
Unrecognized compensation cost related to previously granted stock options	$ 0.3
Unrecognized compensation cost related to previously granted stock options period for recognition	1 year 1 month 6 days
Common Stock Units for Deferred Compensation		222,227	421,846	72,541	64,670