Research and Development and Capitalized Software Development Costs Research and Development and Capitalized Software Development Costs (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Research and Development and Capitalized Software Development Costs [Line Items]
Unamortized software development costs	$ 62.3		$ 62.3		$ 104.9
Capitalized Computer Software, Additions		29.6		61.9
Amortization expense of capitalized costs	20.8	19.8	42.6	48.3
Minimum [Member]
Research and Development and Capitalized Software Development Costs [Line Items]
CapitalizedSoftware, Useful Life	18 months
Maximum [Member]
Research and Development and Capitalized Software Development Costs [Line Items]
CapitalizedSoftware, Useful Life	24 months
Class A Common Stock [Member]
Research and Development and Capitalized Software Development Costs [Line Items]
Capitalized costs included in stock-based compensation		$ 4.2		$ 9.0