Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Patents, at cost	$ 9,859	$ 7,181
Accumulated amortization	(5,071)	(4,780)
Deposits on capital items	22,255	11,886
Right-of-use assets	2,124	2,610
Marlin trade name	7,800
Other	4,655	3,441
Other assets	$ 41,622	$ 20,338