SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - Accounts Receivable-Allowance for Bad Debts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 20,674,000	$ 20,794,000
Additional Charges Against Income	46,555,000	45,387,000
Deductions from Reserve	(32,585,000)	(45,507,000)
Balance at End of Year	$ 34,644,000	$ 20,674,000