Income Taxes - Provision for income taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (8,378,000)	$ 0	$ 11,000
Federal - Foreign	2,660,000	685,000	1,023,000
State and local	5,000	20,000	14,000
Current income tax expense (benefit)	(5,713,000)	705,000	1,048,000
Deferred:
Federal	955,000	738,000	(1,355,000)
Deferred Foreign Income Tax Expense (Benefit)	1,098,000	(1,824,000)	(289,000)
State and local	42,000	26,000	(68,000)
Deferred income tax expense (benefit)	2,095,000	(1,060,000)	(1,712,000)
Provision (benefit) for income taxes	$ (3,618,000)	$ (355,000)	$ (664,000)