SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts
VALUATION AND QUALIFYING ACCOUNTS
Balance at Beginning of period	$ 44,376	$ 43,757	$ 44,553
Charged to Costs and Other Deductions	3,024	2,544	19,132
Charged to Other Accounts	(226)	86	(58)
Deductions	(5,967)	(2,011)	(19,870)
Balance at End of Period	41,207	44,376	43,757
Inventory reserve
VALUATION AND QUALIFYING ACCOUNTS
Balance at Beginning of period	28,934	26,537	46,813
Charged to Costs and Other Deductions		5,897	13,587
Charged to Other Accounts	14,688
Deductions	(15,768)	(3,500)	(33,863)
Balance at End of Period	27,854	28,934	26,537
Valuation allowance on deferred tax assets
VALUATION AND QUALIFYING ACCOUNTS
Balance at Beginning of period	1,869,490	1,807,728	1,560,162
Charged to Other Accounts	47,900	61,762	247,566
Balance at End of Period	$ 1,917,390	$ 1,869,490	$ 1,807,728