Description of the Business and Summary of Significant Accounting Policies - Property and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation	$ 158.6	$ 170.7	$ 173.8
Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum \| Infrastructure Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum \| Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	20 years
Minimum \| Datacenter and other computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum \| Office equipment and other
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Maximum \| Infrastructure Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	4 years
Maximum \| Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	30 years
Maximum \| Datacenter and other computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Maximum \| Office equipment and other
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Change in Accounting Method Accounted for as Change in Estimate
Property, Plant and Equipment [Line Items]
Depreciation	$ (16.1)