Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) revenue_source customer	Mar. 31, 2015 USD ($) customer	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Restricted cash and cash equivalents	$ 400,000		$ 400,000
Impairment of cost method investments	0		0
Capital expenditures incurred but not yet paid	2,300,000	$ 0
Redeemable noncontrolling interests	5,823,000		10,506,000
Additional paid-in capital	3,566,329,000		3,563,848,000
Noncontrolling interests	$ 14,085,000		14,866,000
FolioDynamix
Significant Accounting Policies [Line Items]
Goodwill impairment			$ (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_source	2
Channel Intelligence
Significant Accounting Policies [Line Items]
Proceeds from escrow releases	$ 4,000,000
Correction of Error, Recognition of Permanent Equity | Restatement Adjustment
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interests				$ 4,100,000
Additional paid-in capital				1,400,000
Noncontrolling interests				$ 2,700,000
Actua's Consolidated Revenue
Significant Accounting Policies [Line Items]
Number of customers represented for more than 10% of consolidated revenue | customer	0	0