Cryptocurrencies (Summary of Additional Information About Cryptocurrencies) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Cryptocurrencies, beginning balance	$ 3,839	$ 707
Revenue recognized from cryptocurrencies mined	11,984	6,741
Mining pool operating fees	(146)	(135)
Proceeds from sale of cryptocurrencies	(8,298)	(3,196)
Purchase of miner equipment with cryptocurrencies		(99)
Realized gain on sale/exchange of cryptocurrencies	5,184	665
Impairment of cryptocurrencies	(989)	(844)
Cryptocurrencies received from sale of equipment	52
Cryptocurrencies, ending balance	$ 11,626	$ 3,839