Schedule II - Valuation and Qualifying Accounts (Details) - Valuation Allowance of Deferred Tax Assets [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance at Beginning of Period	$ 6,983	$ 18,109	$ 25,593
Increase	16,293
Decrease		(11,126)	(7,484)
Balance at End of Period	$ 23,276	$ 6,983	$ 18,109

Amount of valuation and qualifying accounts and reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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Amount of increase in valuation and qualifying accounts and reserves from charge to cost and expense.

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Amount of decrease in valuation and qualifying accounts and reserves.

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