CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Revenue	$ 36,709	$ 33,536	$ 71,319	$ 64,128
Operating expenses
Cost of revenue	10,840	9,783	21,032	19,515
Sales and marketing	13,808	12,163	26,967	23,399
General and administrative	13,561	15,966	28,057	31,402
Research and development	7,653	7,373	15,203	14,466
Amortization of intangible assets	4,108	3,706	8,172	7,722
Impairment related and other	117	489	348	835
Total operating expenses	50,087	49,480	99,779	97,339
Operating loss	(13,378)	(15,944)	(28,460)	(33,211)
Other (loss) income, net	(67)	(102)	(223)	1,435
Interest income	39	35	87	54
Interest expense	(71)	(31)	(117)	(68)
Loss before income taxes and noncontrolling interest	(13,477)	(16,042)	(28,713)	(31,790)
Income tax expense	(81)	(1)	(228)	(178)
Net loss	(13,558)	(16,043)	(28,941)	(31,968)
Less: Net loss attributable to the noncontrolling interest	(817)	(761)	(1,869)	(1,921)
Net loss attributable to Actua Corporation	$ (12,741)	$ (15,282)	$ (27,072)	$ (30,047)
Basic and diluted net loss per share attributable to Actua Corporation: (in dollars per share)	$ (0.35)	$ (0.41)	$ (0.73)	$ (0.81)
Shares used in computation of basic and diluted loss per share (in shares)	36,760	37,123	37,027	36,983
Net loss	$ (13,558)	$ (16,043)	$ (28,941)	$ (31,968)
Other comprehensive loss:
Foreign currency translation adjustment	38	0	112	0
Comprehensive loss	(13,520)	(16,043)	(28,829)	(31,968)
Less: Comprehensive loss attributable to the noncontrolling interest	(817)	(761)	(1,869)	(1,921)
Comprehensive loss attributable to Actua Corporation	$ (12,703)	$ (15,282)	$ (26,960)	$ (30,047)