SCHEDULE II Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts
Balance at Beginning of Period	$ 1,525	$ 1,952	$ 695
Charged to (Reduction of) Costs and Expenses	189	(275)	1,321
Taken Against Allowance	(360)	(152)	(64)
Other (Deductions) Recoveries	0	0	0
Balance at End of Period	1,354	1,525	1,952
Valuation on Allowance for Deferred Tax Assets
Balance at Beginning of Period	8,754	6,388	6,202
Charged to (Reduction of) Costs and Expenses	8,135	2,366	186
Taken Against Allowance	0	0	0
Other (Deductions) Recoveries	0	0	0
Balance at End of Period	$ 16,889	$ 8,754	$ 6,388