Consolidated Businesses - Pro Forma Information (Detail) - FolioDynamix, Ludwig, NuCivic, KMI - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2015
Business Acquisition [Line Items]
Revenue	$ 33,972	$ 64,902
Net loss attributable to Actua Corporation	$ (15,772)	$ (30,982)
Net loss per diluted share attributable to Actua Corporation (in dollars per share)	$ (0.42)	$ (0.83)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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