v2.4.0.6
Marketable Securities (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Marketable Securities (Textual) [Abstract]    
Trading securities $ 11.4 $ 10.3
Significant realized or unrealized gains or losses on securities 0 0
Other-than-temporary impairments of marketable securities $ 0 $ 0