Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2014 customer	Jun. 30, 2015 USD ($) revenue_source customer	Jun. 30, 2014 customer	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interests		$ 8,387		$ 10,346
Additional paid-in capital		3,561,691		3,553,430
Noncontrolling interests		$ 17,225		18,288
Actua's Consolidated Revenue
Significant Accounting Policies [Line Items]
Number of customers represented for more than 10% of consolidated revenue | customer	0	0	0
Channel Intelligence
Significant Accounting Policies [Line Items]
Proceeds from escrow releases		$ 4,000
MSDSonline One
Significant Accounting Policies [Line Items]
Number of sources of revenues | revenue_source		2
FolioDynamix
Significant Accounting Policies [Line Items]
Initial subscription arrangement, Minimum		3 years
Initial subscription arrangement, Maximum		5 years
Correction of Error, Recognition of Permanent Equity | Restatement Adjustment
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interests				4,100
Additional paid-in capital				(1,400)
Noncontrolling interests				$ (2,700)