Acquisitions and Divestitures - Intralinks (Details) - USD ($)		3 Months Ended
	Jan. 19, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 224,954,000		$ 224,651,000
Net revenues		86,097,000	$ 78,246,000
Net loss from continuing operations		$ 45,452,000	$ 31,150,000
Intralinks Holdings, Inc.
Business Acquisition [Line Items]
Cash consideration for outstanding Intralinks' common shares	$ 746,071,000
Cash consideration for accelerated equity awards to Intralinks' employees upon change in control	7,873,000
Cash consideration for vested unexercised Intralinks' stock options	19,838,000
Cash consideration for existing Intralinks' debt	77,800,000
Cash consideration for shareholders purchase price settlement	2,794,000
Total cash consideration transferred	854,376,000
Fair value of replacement awards	4,702,000
Total consideration transferred	859,078,000
Cash	39,370,000
Accounts receivable	46,182,000
Prepaid expenses and other assets	9,775,000
Property and equipment, net	$ 14,075,000
Property and equipment, net, weighted average life	4 years
Goodwill	$ 482,822,000
Intangible assets	411,577,000
Other assets, long-term	3,865,000
Investment in unconsolidated affiliate	5,800,000
Total assets	1,013,466,000
Accounts payable	4,853,000
Accrued expenses	21,421,000
Deferred revenues, short-term	12,449,000
Deferred tax liability	110,044,000
Deferred revenues, long-term	1,051,000
Other liabilities, long-term	4,570,000
Total liabilities	154,388,000
Net assets acquired	859,078,000
Tax deductible goodwill	0
Intralinks Holdings, Inc. | Developed Technology Rights
Business Acquisition [Line Items]
Intangible assets	$ 79,400,000
Intangible assets, weighted average life	6 years
Intralinks Holdings, Inc. | Capitalized software costs
Business Acquisition [Line Items]
Intangible assets	$ 277,000
Intangible assets, weighted average life	1 year
Intralinks Holdings, Inc. | Trade Names
Business Acquisition [Line Items]
Intangible assets	$ 47,800,000
Intangible assets, weighted average life	18 years
Intralinks Holdings, Inc. | Customer Relationships
Business Acquisition [Line Items]
Intangible assets	$ 284,100,000
Intangible assets, weighted average life	10 years
Goldman Sachs Bank USA | 2017 Term Facility
Business Acquisition [Line Items]
Borrowing capacity	$ 900,000,000
Proceeds from credit agreement	$ 900,000,000