Summary of Significant Accounting Policies (Prior Period Reclassification Adjustment) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Sales of Investments [Member]  
Summary of Significant Accounting Policies [Line Items]  
Prior Period Reclassification Adjustment $ (14.0)
Maturities of Investments [Member]  
Summary of Significant Accounting Policies [Line Items]  
Prior Period Reclassification Adjustment $ 14.0