Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred income tax assets
Net operating loss carryforwards	$ 51,042		$ 54,909
Capital loss carryforwards	4,417		1,885
Intangible assets - finite life	3,261		6,809
Stock-based compensation	439		716
Property, plant & equipment	3,649		3,587
Deferred rent	799
Deferred rent expense			(64)
Credits	1,281		2,274
Deferred revenue	2,755		2,973
Available-for-sale securities	8,644
Deferred compensation	1,053		1,772
Other	3,585		1,187
Deferred income tax assets	80,925		76,048
Deferred income tax liability - long-term
Intangible assets - Indefinite-lived	(130,818)		(126,443)
Deferred income tax liability - long-term	(130,818)		(126,443)
Less: Valuation Allowance	(17,109)		(17,404)
Net deferred income tax liability - long-term	$ (67,002)	$ (68,262)	$ (67,799)