CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Revenue	$ 34,140	$ 20,762	$ 98,268	$ 58,213
Operating expenses
Cost of Revenue	9,627	5,911	29,142	16,329
Sales and marketing	12,945	10,718	36,344	28,834
General and administrative	14,440	13,798	45,842	36,722
Research and development	7,612	3,960	22,078	10,760
Amortization of intangibles assets	3,728	2,369	11,450	6,963
Impairment related and other	424	256	1,260	1,092
Total operating expenses	48,776	37,012	146,116	100,700
Operating income (loss)	(14,636)	(16,250)	(47,848)	(42,487)
Other income (loss), net	52	83	1,488	1,020
Interest income	34	160	88	392
Interest expense	(36)	(9)	(104)	(1,600)
Income (loss) before income taxes, equity loss and noncontrolling interest	(14,586)	(16,016)	(46,376)	(42,675)
Income tax (expense) benefit	(47)	1,870	(225)	2,375
Equity loss	0	(144)	0	(776)
Income (loss) from continuing operations	(14,633)	(14,290)	(46,601)	(41,076)
Income (loss) from discontinued operations, including gain on sale, net of tax	0	2,426	0	3,789
Net income (loss)	(14,633)	(11,864)	(46,601)	(37,287)
Less: Net income (loss) attributable to the noncontrolling interest	(751)	(1,184)	(2,672)	(3,563)
Net income (loss) attributable to Actua Corporation	(13,882)	(10,680)	(43,929)	(33,724)
Amounts attributable to Actua Corporation:
Net income (loss) from continuing operations	(13,882)	(13,106)	(43,929)	(37,513)
Net income (loss) from discontinued operations	0	2,426	0	3,789
Net income (loss) attributable to Actua Corporation	$ (13,882)	$ (10,680)	$ (43,929)	$ (33,724)
Basic and diluted income (loss) per share attributable to Actua Corporation:
Income (loss) from continuing operations (in dollars per share)	$ (0.37)	$ (0.35)	$ (1.19)	$ (1.01)
Income (loss) from discontinued operations (in dollars per share)	0.00	0.06	0.00	0.10
Net income (loss) (in dollars per share)	$ (0.37)	$ (0.29)	$ (1.19)	$ (0.91)
Shares used in computation of basic and diluted income (loss) per share	37,146	37,335	37,038	37,248
Net income (loss)	$ (14,633)	$ (11,864)	$ (46,601)	$ (37,287)
Other comprehensive income
Unrealized holding gain (loss) in marketable securities	0	0	0	0
Reclassified adjustments/realized net (gains) loss on marketable securities	0	0	0	0
Other accumulated other comprehensive income (loss)	0	0	0	0
Comprehensive income (loss)	(14,633)	(11,864)	(46,601)	(37,287)
Less: Comprehensive income (loss) attributable to noncontrolling interests	(751)	(1,184)	(2,672)	(3,563)
Comprehensive income (loss) attributable to Actua Corporation	$ (13,882)	$ (10,680)	$ (43,929)	$ (33,724)