Other Assets - Investments - Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Equity Securities
Investments - equity securities	$ 375		$ 375		$ 2,623
Unrealized gain (loss) on investments held as of balance sheet date	100	$ 300	(900)	$ (4,500)
Preferred stock
Equity Securities
Investments - equity securities	$ 400		$ 400		$ 2,600