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STOCKHOLDERS' EQUITY - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2016
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	$ 0	$ 126	$ 0	$ 250
Aggregate intrinsic value of options exercised	9,717		11,734
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	1,835	1,946	$ 3,225	3,876
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	831		$ 7,721
Unrecognized stock-based compensation expense	4,600		4,600
Maximum | Performance-Based Stock Units
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	7,096		$ 7,096
Weighted Average | Restricted Stock and Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense, weighted average period			1 year 7 months 6 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 6 days
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	$ 54	$ 48	$ 95	$ 71
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)	1,398,000		1,398,000
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		$ 29.50
Sale of stock, net proceeds			$ 100,446

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