Investments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Equity Securities without Readily Determinable Fair Value
Cost of investments	$ 8,333,000		$ 8,333,000		$ 3,000,000
Cumulative impairment	0		0		0
Cumulative upward adjustment	5,314,000		5,314,000		5,314,000
Carrying amount of investments	13,647,000		13,647,000		$ 8,314,000
Equity Securities, Gain (Loss)
Realized gain (loss)	0	$ 0	0	$ 0
Unrealized gain	$ 0	$ 0	$ 0	$ 0