Equity, Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Other comprehensive gain before reclassifications			$ 15,700,000
Amount reclassified from accumulated other comprehensive income			(900,000)
Other comprehensive gains, net			14,800,000
Other expense, net	$ 11,600,000	$ 17,100,000	33,800,000	$ 32,900,000
Cost of revenues	464,900,000	440,700,000	871,900,000	850,800,000
Sales and marketing	243,700,000	232,400,000	475,500,000	452,600,000
General and administrative	58,600,000	56,300,000	118,000,000	111,500,000
Research and development expense	247,900,000	$ 251,600,000	498,900,000	$ 500,300,000
Unrealized Gains (Losses) on Available-for- Sale Securities [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2015			17,000,000
Other comprehensive gain before reclassifications			6,000,000
Amount reclassified from accumulated other comprehensive income			(800,000)
Other comprehensive gains, net			5,200,000
Balance as of June 30, 2016	22,200,000		22,200,000
Unrealized Gains (Losses) on Available-for- Sale Securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Other expense, net			(800,000)
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2015			(1,300,000)
Other comprehensive gain before reclassifications			3,900,000
Amount reclassified from accumulated other comprehensive income			(100,000)
Other comprehensive gains, net			3,800,000
Balance as of June 30, 2016	2,500,000		2,500,000
Unrealized Gains (Losses) on Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Cost of revenues			100,000
Sales and marketing			(100,000)
Research and development expense			(100,000)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2015			(34,900,000)
Other comprehensive gain before reclassifications			5,800,000
Amount reclassified from accumulated other comprehensive income			(0.0)
Other comprehensive gains, net			5,800,000
Balance as of June 30, 2016	(29,100,000)		(29,100,000)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2015			(19,200,000)
Balance as of June 30, 2016	$ (4,400,000)		$ (4,400,000)