Basis of Presentation and Informational Disclosures (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock-based aggregate disclosure
Stock-based employee compensation expense	$ 1.2	$ 1.1
Income Taxes- Uncertain Tax Positions
Unrecognized tax benefits liability	0
Accrued amount of payment of interest or penalties	0
Stock options
Stock-based aggregate disclosure
Compensation expense for unvested common share awards which is yet to be recognized	4.9
Restricted common shares
Stock-based aggregate disclosure
Compensation expense for unvested common share awards which is yet to be recognized	$ 14.6