SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts, Activity for the years ended December 31, 2016, 2015 and 2014 was as follows:
Balance at Beginning of Year	$ 10,613	$ 10,353	$ 8,668
Additions, Charged to Costs and Expenses	5,260	1,260	1,685
Additions, Charged to Other Accounts	0	0	0
Deductions	4,241	1,000	0
Balance at End of Year	11,632	10,613	10,353
Allowance for doubtful accounts [Member]
Valuation and Qualifying Accounts, Activity for the years ended December 31, 2016, 2015 and 2014 was as follows:
Balance at Beginning of Year	726	726	608
Additions, Charged to Costs and Expenses	350	0	118
Additions, Charged to Other Accounts	0	0	0
Deductions	0	0	0
Balance at End of Year	1,076	726	726
Deferred tax valuation allowance [Member]
Valuation and Qualifying Accounts, Activity for the years ended December 31, 2016, 2015 and 2014 was as follows:
Balance at Beginning of Year	9,887	9,627	8,060
Additions, Charged to Costs and Expenses	4,910	1,260	1,567
Additions, Charged to Other Accounts	0	0	0
Deductions	4,241	1,000	0
Balance at End of Year	$ 10,556	$ 9,887	$ 9,627