Equity, Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, Beginning balance				$ 4.7
Other comprehensive gain (loss) before reclassifications				(6.1)
Amount reclassified from accumulated other comprehensive (gain) income				(2.3)
Other comprehensive income (loss), net of tax	1.5		(7.6)	(8.4)		9.3
Accumulated other comprehensive (loss) income, Ending balance	(3.7)			(3.7)
Other (expense) income, net	(12.6)		2.8	(22.7)		(21.6)
Cost of revenues	430.2		405.9	818.6		804.3
Research and development	257.7		268.7	519.9		538.3
Sales and marketing	266.2		259.5	521.4		517.2
General and administrative	48.8		48.8	96.6		103.5
Unrealized gains (losses) on available-for-sale securities [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, Beginning balance				2.1	[1]
Other comprehensive gain (loss) before reclassifications				5.6	[1]
Amount reclassified from accumulated other comprehensive (gain) income				(0.5)	[1]
Other comprehensive income (loss), net of tax				5.1	[1]
Accumulated other comprehensive (loss) income, Ending balance	7.2	[1]		7.2	[1]
Other (expense) income, net				0.5
Unrealized gains (losses) on cash flow hedges [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, Beginning balance				3.0	[2]
Other comprehensive gain (loss) before reclassifications				(2.2)	[2]
Amount reclassified from accumulated other comprehensive (gain) income				(1.8)	[2]
Other comprehensive income (loss), net of tax				(4.0)	[2]
Accumulated other comprehensive (loss) income, Ending balance	(1.0)	[2]		(1.0)	[2]
Cost of revenues				0.2
Research and development				0.8
Sales and marketing				0.4
General and administrative				0.4
Foreign currency translation adjustments [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Accumulated other comprehensive (loss) income, Beginning balance				(0.4)
Other comprehensive gain (loss) before reclassifications				(9.5)
Amount reclassified from accumulated other comprehensive (gain) income				0
Other comprehensive income (loss), net of tax				(9.5)
Accumulated other comprehensive (loss) income, Ending balance	$ (9.9)			$ (9.9)

[1] The reclassifications out of accumulated comprehensive income during the six months ended June 30, 2013 for realized gains on available-for-sale securities of $0.5 million are included in other (expense) income, net in the Condensed Consolidated Statements of Operations.

[2] The reclassifications out of accumulated comprehensive income during the six months ended June 30, 2013 for realized gains on cash flow hedges are included within cost of revenues of $0.2 million, research and development of $0.8 million, sales and marketing of $0.4 million, and general and administrative of $0.4 million for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.