SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for doubtful accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in valuation and qualifying accounts
Balance at Beginning of Period	$ 7,715	$ 6,565	$ 7,885
Charged to Costs and Expenses	1,056	4,533	2,196
Deductions	(3,666)	(3,383)	(3,516)
Balance at End of Period	$ 5,105	$ 7,715	$ 6,565