Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Sales commissions and fees	$ 22.1	$ 19.2	$ 17.0
Foreign currency transaction losses	$ 1.4	1.9	$ 0.3
Computer equipment and capitalized software
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Software development costs
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Minimum
Property, Plant and Equipment [Line Items]
Revenue recognition period	2 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Maximum
Property, Plant and Equipment [Line Items]
Revenue recognition period	4 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	11 years
Adjustments for New Accounting Principle, Early Adoption
Property, Plant and Equipment [Line Items]
Decrease to current deferred tax assets		9.6
Decrease to long-term deferred tax liabilities		$ 9.6