Acquisitions - Allocation of Purchase Price (Details) - USD ($) $ in Thousands	Sep. 30, 2015	May. 18, 2015	Jan. 08, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 1,957,436			$ 1,796,851
Sanbolic, Inc. [Member]
Business Acquisition [Line Items]
Current assets			$ 581
Property and equipment			0
Intangible assets			45,300
Goodwill			61,639
Other assets			0
Assets acquired			107,520
Current liabilities assumed			1,454
Long-term liabilities assumed			3,175
Deferred tax liabilities, non-current			13,295
Net assets acquired			$ 89,596
Grasshopper Group, LLC [Member]
Business Acquisition [Line Items]
Current assets		$ 4,818
Property and equipment		467
Intangible assets		71,400
Goodwill		99,686
Other assets		80
Assets acquired		176,451
Current liabilities assumed		11,181
Long-term liabilities assumed		158
Deferred tax liabilities, non-current		0
Net assets acquired		$ 165,112