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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - $ / shares
3 Months Ended 12 Months Ended
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Accounting Policies [Abstract]            
Percentage of LIFO Inventory       24.00% 24.00%  
Percentage of FIFO Inventory       70.00% 67.00%  
Percentage of Weighted Average Cost Inventory       6.00% 9.00%  
Dividends declared (in dollars per share) $ 0.46 $ 0.46 $ 0.46   $ 1.38 $ 1.84
Minimum            
Finite-Lived Intangible Assets [Line Items]            
Useful life       3 years    
Maximum            
Finite-Lived Intangible Assets [Line Items]            
Useful life       20 years    
Asset retirement obligations, estimated remaining useful life       10 years