Annual report pursuant to Section 13 and 15(d)

FAIR VALUE MEASUREMENTS (Fair Value of Assets Measured on Non-recurring Basis) (Details)

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FAIR VALUE MEASUREMENTS (Fair Value of Assets Measured on Non-recurring Basis) (Details) - USD ($)
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Goodwill impairment $ 20,000,000   $ 20,000,000 $ 0 $ 0
Impairment charge, investments in nonconsolidated affiliates   $ 15,100,000   16,455,000  
Gain on consolidation of nonconsolidated affiliates         $ 9,100,000
Fair Value, Measurements, Nonrecurring [Member]          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Goodwill, Fair Value Disclosure 30,832,000   30,832,000    
Investments in nonconsolidated affiliates       0  
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Goodwill, Fair Value Disclosure 0   0    
Investments in nonconsolidated affiliates       0  
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Goodwill, Fair Value Disclosure 0   0    
Investments in nonconsolidated affiliates       0  
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Goodwill, Fair Value Disclosure $ 30,832,000   $ 30,832,000    
Investments in nonconsolidated affiliates       $ 0