Equity and Cost Method Businesses	12 Months Ended
Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity and Cost Method Businesses	Equity and Cost Method Businesses Equity Method Businesses Actua did not own any equity method businesses during 2016 and wound down and ceased its operations in Acquirgy, Inc. ("Acquirgy") in early 2015. During the year ended December 31, 2014, CIML LLC (of which Actua held voting ownership of 38%) ceased operations. During that year, these equity method businesses had revenue of $8.8 million and net loss of $1.1 million, from which Actua recognized equity loss of $0.8 million, including $0.1 million of amortization expense. Cost Method Businesses Actua’s carrying value of its holdings in cost method businesses was $17.3 million as of December 31, 2016 and $18.1 million as of December 31, 2015, as reflected in the line item "Cost method businesses" in Actua’s Consolidated Balance Sheets as of the relevant dates. Actua owns approximately 9% of Anthem Ventures Fund, L.P. (formerly eColony, Inc.) and Anthem Ventures Annex Fund, L.P. (collectively, "Anthem"), which invest in technology companies. Actua acquired its interest in Anthem in 2000 and currently has no carrying value in Anthem. Accordingly, the receipt of distributions from Anthem by Actua would result in a gain at the time Actua receives those distributions. During the year ended December 31, 2015, Actua received a distribution from Anthem that resulted in proceeds of $1.0 million, and recorded a gain in that amount. In March 2017, Actua received a distribution from Anthem of both shares and $866 thousand of cash. A gain will be recognized during the first quarter of 2017 for the value of the cash and shares received. See Note 13, "Other Income (Loss), Net," for additional information. During the year ended December 31, 2016, Actua increased its interest in Parchment Inc. ("Parchment"), a cost method business, by $0.7 million. Actua also elected to sell a portion of its interest in InstaMed Holdings, Inc. ("InstaMed"), a cost method business, pursuant to a tender offer. This sale resulted in a $1.6 million decrease in Actua's interest in InstaMed, as well as a gain of $2.8 million. See Note 13, "Other Income (Loss), Net," for additional information. Impairments Actua performs ongoing business reviews of its cost method businesses to determine whether Actua’s carrying value in those businesses is impaired. Actua determined its carrying value in its cost method businesses was not impaired during the years ended December 31, 2016, 2015 and 2014.

Equity and Cost Method Businesses

Equity Method Businesses

Actua did not own any equity method businesses during 2016 and wound down and ceased its operations in Acquirgy, Inc. ("Acquirgy") in early 2015. During the year ended December 31, 2014, CIML LLC (of which Actua held voting ownership of 38%) ceased operations. During that year, these equity method businesses had revenue of $8.8 million and net loss of $1.1 million, from which Actua recognized equity loss of $0.8 million, including $0.1 million of amortization expense.

Cost Method Businesses

Actua’s carrying value of its holdings in cost method businesses was $17.3 million as of December 31, 2016 and $18.1 million as of December 31, 2015, as reflected in the line item "Cost method businesses" in Actua’s Consolidated Balance Sheets as of the relevant dates.

Actua owns approximately 9% of Anthem Ventures Fund, L.P. (formerly eColony, Inc.) and Anthem Ventures Annex Fund, L.P. (collectively, "Anthem"), which invest in technology companies. Actua acquired its interest in Anthem in 2000 and currently has no carrying value in Anthem. Accordingly, the receipt of distributions from Anthem by Actua would result in a gain at the time Actua receives those distributions. During the year ended December 31, 2015, Actua received a distribution from Anthem that resulted in proceeds of $1.0 million, and recorded a gain in that amount. In March 2017, Actua received a distribution from Anthem of both shares and $866 thousand of cash. A gain will be recognized during the first quarter of 2017 for the value of the cash and shares received. See Note 13, "Other Income (Loss), Net," for additional information.

During the year ended December 31, 2016, Actua increased its interest in Parchment Inc. ("Parchment"), a cost method business, by $0.7 million. Actua also elected to sell a portion of its interest in InstaMed Holdings, Inc. ("InstaMed"), a cost method business, pursuant to a tender offer. This sale resulted in a $1.6 million decrease in Actua's interest in InstaMed, as well as a gain of $2.8 million. See Note 13, "Other Income (Loss), Net," for additional information.

Impairments

Actua performs ongoing business reviews of its cost method businesses to determine whether Actua’s carrying value in those businesses is impaired. Actua determined its carrying value in its cost method businesses was not impaired during the years ended December 31, 2016, 2015 and 2014.