Goodwill and Purchased Intangible Assets, Finite Lived Intangible Assets by Class (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 9.5	$ 7.5
Cost of Revenues [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	8.2	6.3
Sales and Marketing Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	1.0	0.9
General and Administrative Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	0.3	0.3
Operating expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 1.3	$ 1.2