Acquisitions - Purchase of an Asset Group Constituting a Business - ECD Business (Details) - USD ($) $ in Thousands	Jan. 23, 2017	Dec. 31, 2017	Jun. 30, 2017
Purchase Price Allocation
Goodwill		$ 3,578,976	$ 3,416,749
ECD Business
Business Acquisition [Line Items]
Purchase consideration	$ 1,620,000
Purchase Price Allocation
Current assets	11,339
Non-current tangible assets	103,672
Liabilities assumed	(182,301)
Total identifiable net assets	798,710
Goodwill	823,684
Net assets acquired	1,622,394
Goodwill expected to be tax deductible	378,500
Deferred revenue	163,800
Deferred revenue adjustment	52,000
Contract assets acquired	8,400
ECD Business | Customer assets
Purchase Price Allocation
Acquired intangible assets	407,000
ECD Business | Technology assets
Purchase Price Allocation
Acquired intangible assets	$ 459,000