Actua Corporation's Stockholders' Equity - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) Vote shares	Dec. 31, 2015 shares
Equity [Abstract]
Number of votes per share | Vote	1
Dividends | $	$ 0
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0