Schedule II - Consolidated Valuation and Qualifying Accounts (Details 2) - Allowance for doubtful accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for doubtful accounts:
Balance, beginning of period	$ 8,069	$ 10,479	$ 9,835
Charged to costs and expenses	7,532	7,024	8,302
Other	1,121	989	851
Deductions	7,872	10,423	8,509
Balance, end of period	$ 8,850	$ 8,069	$ 10,479