Consolidated Businesses - Additional Information (Detail) - USD ($) $ in Thousands						1 Months Ended	3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 22, 2016	Nov. 25, 2015	Jul. 13, 2015	Jun. 10, 2015	Nov. 03, 2014	Jul. 31, 2016	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Impact of subsidiary equity transactions								$ 1,549	$ 3,243
Payments to acquired additional interest in subsidiaries								5,400	4,000
Actua's share of consolidated business equity transactions								(3,900)
Additional Paid-In Capital
Business Acquisition [Line Items]
Impact of subsidiary equity transactions								1,526	$ 2,533
FolioDynamix
Business Acquisition [Line Items]
Cash paid for acquisition					$ 201,700
Rolled stock options acquired					$ 4,100
FolioDynamix | Adjustment
Business Acquisition [Line Items]
Post-closing working capital adjustment							$ 700
TMGov | GovDelivery
Business Acquisition [Line Items]
Cash paid for acquisition				$ 400						$ 100
Business acquisition, consideration transferred				500
Business combination consideration transferred, liabilities incurred				$ 100
Textizen | GovDelivery
Business Acquisition [Line Items]
Cash paid for acquisition			$ 1,200
Contingent consideration, asset			$ 400
WellNet | VelocityEHS
Business Acquisition [Line Items]
Cash paid for acquisition		$ 700						$ 2,200
Intangible assets recorded in acquisition		$ 2,900
ErgoAdvocate | VelocityEHS
Business Acquisition [Line Items]
Cash paid for acquisition	$ 1,000
Business acquisition, consideration transferred	1,250
Liabilities incurred to be paid in one year	$ 250
Subsequent Event | Textizen | GovDelivery
Business Acquisition [Line Items]
Payments To Acquire Businesses, Retained By Acquirer						$ 400