Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance at Beginning of Period	$ 17,112	$ 16,116	$ 16,178
Valuation Allowances and Reserves, Additions	1,775	1,912	2,207
Valuation Allowances and Reserves, Deductions	5,968	916	2,269
Valuation Allowances and Reserves, Balance at End of Period	$ 12,919	$ 17,112	$ 16,116