Investments (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Investments [Abstract]
Long Term Investments Maturity Period Description	Greater than one year	Greater than one year
Short Term Investments Maturity Period Description	Greater than three months and up to one year	Greater than three months and up to one year
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales and maturities of debt securities	$ 0.4	$ 12.9
Payments to acquire available-for-sale securities, debt	2.0	4.6
Available-for-sale securities, gross realized gains	0.1	0.1
Other-than-temporary losses on investments	$ 0	$ 0