Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) customer	Jun. 30, 2015 USD ($) customer	Jun. 30, 2016 USD ($) revenue_source customer	Jun. 30, 2015 USD ($) customer	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents	$ 600,000		$ 600,000		$ 600,000
Impairment of cost method investments			0		0
Capital expenditures incurred but not yet paid	400,000	$ 0	2,200,000	$ 0
Redeemable noncontrolling interests	6,362,000		6,362,000		10,506,000
Additional paid-in capital	3,570,053,000		3,570,053,000		3,563,848,000
Noncontrolling interests	$ 13,261,000		$ 13,261,000		14,866,000
Actua's Customer Concentration Risk | Consolidated Revenue
Significant Accounting Policies [Line Items]
Number of customers represented for more than 10% of consolidated revenue | customer	0	0	0	0
Restatement Adjustment | Correction of Error, Recognition of Permanent Equity
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interests						$ 4,100,000
Additional paid-in capital						(1,400,000)
Noncontrolling interests						$ (2,700,000)
FolioDynamix
Significant Accounting Policies [Line Items]
Impairment loss					$ 39,700,000
Initial subscription arrangement, minimum			3 years
Initial subscription arrangement, maximum			5 years
Bolt
Significant Accounting Policies [Line Items]
Subscription Period			1 month
GovDelivery
Significant Accounting Policies [Line Items]
Customer contract cancellation period			30 days
VelocityEHS
Significant Accounting Policies [Line Items]
Number of sources of revenues (revenue sources) | revenue_source			2
Channel Intelligence
Significant Accounting Policies [Line Items]
Proceeds from escrow releases	$ 4,000,000		$ 4,000,000