VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowances for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 572	$ 1,443	$ 4,919
Charged (Credited) to Costs and Expenses	222	949	1,834
Deductions	(364)	(1,820)	(5,310)
Balance at End of Year	430	572	1,443
Allowances for doubtful notes receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	4,000	4,000	4,000
Charged (Credited) to Costs and Expenses	0	0	0
Deductions	0	0	0
Balance at End of Year	4,000	4,000	4,000
Valuation allowance on deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	153,463	217,589	194,255
Charged (Credited) to Costs and Expenses	7,042	(64,126)	23,334
Deductions	0	0	0
Balance at End of Year	160,505	153,463	217,589
Excess and obsolete inventory
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	15,039	15,049	24,475
Charged (Credited) to Costs and Expenses	665	398	429
Deductions	(680)	(408)	(9,855)
Balance at End of Year	$ 15,024	$ 15,039	$ 15,049