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STOCKHOLDERS' EQUITY - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2016
Stock Options |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | $ 0 | $ 124 |
Aggregate intrinsic value of options exercised | 2,017 |  |
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | $ 1,390 | 1,930 |
Restricted Stock Awards | Non-Employee Director |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 3 years |  |
Restricted Stock and Restricted Stock Unit |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Total fair value of other stock awards vested | $ 6,890 |  |
Unrecognized stock-based compensation expense | 4,607 |  |
Maximum | Performance-Based Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense | $ 3,786 |  |
Weighted Average | Restricted Stock and Restricted Stock Unit |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense, weighted average period | 1 year 10 months 4 days |  |
Weighted Average | Performance-Based Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense, weighted average period | 1 year 1 month |  |
2016 Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options granted period | 10 years |  |
2016 Plan | Minimum |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 1 year |  |
2016 Plan | Maximum |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 4 years |  |
Amended and Restated 1997 Employee Stock Purchase Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | $ 41 | $ 23 |
Class A Common Stock | 2016 Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Common stock, authorized shares (in shares) |  |  | 2,250,000
Number of shares available for future grant (in shares) | 1,553,000 |  |
Class A Common Stock | 2006 Incentive Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Common stock, additional authorized shares (in shares) |  |  | 2,723,000
Public Stock Offering | Class A Common Stock |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Sale of stock, number of shares issued (in shares) | 3,565,000 |  |
Sale of stock, price per share (in dollars per share) | $ 29.50 |  |
Sale of stock, net proceeds | $ 100,446 |  |

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