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STOCKHOLDERS' EQUITY - Narrative (Detail) $ / shares in Units, $ in Thousands | 12 Months Ended
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Dec. 31, 2020 USD ($) vote $ / shares shares | Dec. 31, 2019 USD ($) vote $ / shares shares | Dec. 31, 2018 USD ($)
Limited Partners' Capital Account [Line Items] |  |  |
Reduction of goodwill |  | $ 2,619 |
Preferred stock authorized to issue (up to) (in shares) | shares | 944,000 |  |
Shares issued | shares | 0 | 0 |
Total fair value of other stock awards vested | $ 18,329 | $ 8,177 | $ 10,529
Restricted Stock Awards |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense | 76 |  |
Stock Options |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | 0 | 0 | 474
Aggregate intrinsic value of stock options exercised | 296 | 19,475 | 1,916
Restricted Stock, Restricted Stock Units and Performance Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | 7,965 | 7,036 | 7,821
Income benefit associated with stock-based compensation expense | 6,796 | 97 | 23
Restricted Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense | $ 3,751 |  |
Market-based Performance Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Weighted average fair value of market-based performance (in dollars per share) | $ / shares | $ 50.25 |  |
Risk-free interest rate | 0.57% |  |
Expected volatility | 31.00% |  |
Expected dividend yield | 0.00% |  |
Amended and Restated 1997 Employee Stock Purchase Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Stock-based compensation expense | $ 254 | $ 186 | $ 150
Non-Employee Director | Restricted Stock Awards |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 3 years |  |
Maximum | Performance Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense | $ 4,597 |  |
Weighted Average | Restricted Stock Awards |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense, weighted average period | 2 years 3 months 18 days |  |
Weighted Average | Restricted Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense, weighted average period | 1 year 9 months 18 days |  |
Weighted Average | Performance Stock Units |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Unrecognized stock-based compensation expense, weighted average period | 1 year 8 months 12 days |  |
2016 Incentive Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options granted period | 10 years |  |
2016 Incentive Plan | Minimum |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 1 year |  |
2016 Incentive Plan | Maximum |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Options vesting period | 4 years |  |
Class A Common Stock |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Vote for each share held (in votes per share) | vote | 1 |  |
Number of shares available for future grant | shares | 74,000 |  |
Class A Common Stock | Public Stock Offering |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Sale of stock, number of shares issued | shares | 2,703,000 | 3,565,000 |
Sale of stock, price per share (in dollars per share) | $ / shares | $ 56.00 | $ 29.50 |
Sale of stock, net proceeds | $ 144,790 | $ 100,446 |
Class A Common Stock | Unregistered Sale |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Sale of stock, number of shares issued | shares |  | 59,000 |
Sale of stock, price per share (in dollars per share) | $ / shares |  | $ 44.15 |
Sale of stock, net proceeds |  | $ 2,619 |
Class A Common Stock | 2016 Incentive Plan |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Common stock, authorized shares | shares | 2,250,000 |  |
Common stock, additional authorized shares | shares | 2,723,000 |  |
Number of shares available for future grant | shares | 1,104,000 |  |
Class B Common Stock |  |  |
Limited Partners' Capital Account [Line Items] |  |  |
Vote for each share held (in votes per share) | vote | 10 | 10 |

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