Segments, Geographical (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Revenues by Geographic Region [Line Items]
Total net revenues	$ 1,319.6	$ 1,248.6	$ 1,222.2	$ 1,067.4	$ 1,101.6	$ 1,125.9	$ 1,229.5	$ 1,170.1	$ 4,857.8	$ 4,627.1	$ 4,669.1
Property and equipment, net and purchased intangible assets, net	1,054.9				966.7				1,054.9	966.7
United States [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									2,568.6	2,410.6	2,381.5
Property and equipment, net and purchased intangible assets, net	925.5				871.7				925.5	871.7
Other Americas [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									223.6	219.7	232.0
Americas [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									2,792.2	2,630.3	2,613.5
EMEA [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									1,320.3	1,263.3	1,256.9
Asia Pacific [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									745.3	733.5	$ 798.7
International [Member]
Net Revenues by Geographic Region [Line Items]
Property and equipment, net and purchased intangible assets, net	$ 129.4				$ 95.0				$ 129.4	$ 95.0