Schedule II - Valuation and Qualifying Accounts - Summary of Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Balance at Beginning of Period	$ 1,610	$ 1,385	$ 1,299
Additions Charged to Costs and Expenses	575	641	369
Additions Charged to Other Accounts
Deductions	(245)	(416)	(283)
Balance at End of Period	1,940	1,610	1,385
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
Balance at Beginning of Period	2,379	2,017	1,030
Additions Charged to Costs and Expenses		362	987
Additions Charged to Other Accounts
Deductions	(324)
Balance at End of Period	$ 2,055	$ 2,379	$ 2,017