Quarterly report pursuant to Section 13 or 15(d)

STOCKHOLDERS' EQUITY - Narrative (Details)

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STOCKHOLDERS' EQUITY - Narrative (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Payment of dividends $ 30,602 $ 25,058  
Dividends paid (in dollars per share) $ 0.14 $ 0.115  
Number of shares repurchased (in shares) 0 0  
Repurchase of common stock $ 9,225 $ 7,500 $ 8,246
Common stock reserved for issuance (in shares) 3,900,000    
Unvested restricted stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized compensation cost $ 48,100   $ 32,900
Unrecognized compensation cost, period for recognition 4 years 6 months 12 days   3 years 10 months 24 days