Summary of Significant Accounting Policies (Details-2) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	$ 44,738,000	$ 23,481,000
Restricted cash	644,000	619,000
Receivable - margin account	1,657,000	1,714,000
Cash, cash equivalents, and restricted cash	47,039,000	25,814,000	$ 84,929,000	$ 112,094,000
MGE [Member]
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	4,103,000	3,196,000
Restricted cash	644,000	619,000
Receivable - margin account	1,657,000	1,714,000
Cash, cash equivalents, and restricted cash	$ 6,404,000	$ 5,529,000	$ 6,670,000	$ 10,093,000