Investments (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 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	$ 4.6	$ 4.1	$ 5.0	$ 17.0
Payments to acquire available-for-sale securities, debt	2.2	5.1	4.2	9.7
Proceeds from the maturity of short-term investments		4.8	0	4.8
Available-for-sale securities, gross realized gains less than	0.1	0.1	0.1	0.1
Other-than-temporary impairment losses on investments	0	21.5	0	21.5
Held-to-maturity investments	$ 0		$ 0		$ 0