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STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2019
Mar. 31, 2019
Dec. 31, 2018
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Dec. 31, 1999
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Options outstanding (in shares)   0   0   0    
Share based compensation, shares authorized (in shares)   15,825,223            
Share based compensation, shares authorized for future grant (in shares)   3,143,694            
Intrinsic value of nonvested restricted stock awards expected to vest   $ 16,800            
Unrecognized compensation related to non-vested awards   $ 8,300            
Unrecognized compensation costs, weighted average period expected to be recognized (years)   2 years            
Proceeds from employee common stock purchases   $ 1,443   $ 1,382   $ 1,330    
One-time Termination Benefits                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
One time cash payment   1,500            
Stock based compensation expense   $ 1,100            
Service-based Restricted Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares granted in period (in shares)   362,459            
Forfeited shares (in shares)   38,033            
Vested (in shares)   329,343            
Share based compensation, fair value of restricted stock vested   $ 5,500   $ 5,100   $ 4,700    
Granted (in usd per share)   $ 16.96   $ 14.15   $ 21.46    
Service-based Restricted Shares | One-time Termination Benefits                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Vested (in shares)   44,507            
Performance Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares granted in period (in shares)   111,135            
Share based compensation, annual award vesting period from date of grant   3 years   3 years   3 years    
Forfeited shares (in shares)   96,955            
Vested (in shares)   102,309            
Share based compensation, fair value of restricted stock vested   $ 1,800   $ 0   $ 1,200    
Granted (in usd per share)   $ 17.27   $ 13.70   $ 22.00    
Performance Shares | One-time Termination Benefits                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Vested (in shares)   37,463            
Performance Period 2016 to 2018 | Performance Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares earned in period (in shares)   64,846            
Share based compensation, dividend earned on shares subject to the awards (in shares)   4,226            
Forfeited shares (in shares)   73,345            
Performance Period 2015 to 2017 | Performance Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Forfeited shares (in shares)       91,820        
Performance Period 2017 to 2019 | Performance Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Forfeited shares (in shares)           87,241    
Employees and executives | Service based awards | Service-based Restricted Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares granted in period (in shares)   311,566            
Share based compensation, award granted in period grant-date fair value   $ 5,300            
Share based compensation, annual award vesting period from date of grant   1 year            
Employees and executives | Service based awards | Service-based Restricted Shares | Share-based Compensation Award, Tranche One                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award annual installment vesting rate   25.00%            
Employees and executives | Performance based awards | Service-based Restricted Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares granted in period (in shares) 111,135              
Share based compensation, award granted in period grant-date fair value $ 1,900              
Share based compensation, annual award vesting period from date of grant 3 years              
Non employee directors | Service based awards | Service-based Restricted Shares                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, award shares granted in period (in shares)   47,560            
Share based compensation, award granted in period grant-date fair value   $ 800            
Share based compensation, annual award vesting period from date of grant   1 year            
Employee stock                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share based compensation, shares authorized (in shares)               2,321,688
Share based compensation, shares authorized for future grant (in shares)   890,981            
Proceeds from employee common stock purchases     $ 1,400   $ 1,400   $ 1,300