| Component: (Network and Table) | |
|---|---|
| Network | 2427404 - Disclosure - Equity-Based Compensation - Share Activity with Respect to Restricted Stock (Detail) (http://www.actua.com/role/EquityBasedCompensationShareActivityWithRespectToRestrictedStockDetail) |
| Table | Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] |
| Reporting Entity [Axis] | 0001085621 (http://www.sec.gov/CIK) |
| Award Type [Axis] | Restricted stock |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | Period [Axis] | ||
|---|---|---|---|
2016-01-01 - 2016-12-31 | 2015-01-01 - 2015-12-31 | 2014-01-01 - 2014-12-31 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] | |||
Number of Shares, Issued and unvested, beginning of period (in shares) | |||
Number of Shares, Granted (in shares) | |||
Number of shares, Vested (in shares) | ( | ( | ( |
Number of Shares, Forfeited (in shares) | ( | ( | ( |
Number of Shares, Issued and unvested, end of period (in shares) | 3,480,828 | 3,755,275 | |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] | |||
Weighted Average Grant Date Fair Value, Issued and unvested beginning balance (in dollars per share) | |||
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | |||
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | |||
Weighted Average Grant Fate Fair Value, Forfeited (in dollars per share) | |||
Weighted Average Grant Date Fair Value, Issued and unvested ending balance (in dollars per share) | 15.82 | 15.94 | |
Shares surrendered by employees for withholding taxes (in shares) | |||