Summary of Significant Accounting Policies (Details-2) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	$ 23,481,000	$ 83,102,000
Restricted cash	619,000	634,000
Receivable - margin account	1,714,000	1,193,000
Cash, cash equivalents, and restricted cash	25,814,000	84,929,000	$ 112,094,000	$ 101,633,000
MGE [Member]
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	3,196,000	4,843,000
Restricted cash	619,000	634,000
Receivable - margin account	1,714,000	1,193,000
Cash, cash equivalents, and restricted cash	$ 5,529,000	$ 6,670,000	$ 10,093,000	$ 16,442,000