Net Periodic Benefit Cost-Defined Benefit Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Net periodic benefit cost of the domestic non-contributory defined benefit plan
Interest cost	$ 161,000	$ 191,000	$ 481,000	$ 573,000
Expected return on plan assets	(330,000)	(248,000)	(956,000)	(746,000)
Amortization of net loss	52,000	46,000	144,000	140,000
Net periodic benefit	(117,000)	$ (11,000)	(331,000)	$ (33,000)
Expected contribution to Pension Plan (minimum)					$ 500,000
Employer contributions made to the defined benefit plan			1,250,000
Anticipated additional contributions anticipated during the remainder of the year (at least)	$ 250,000		$ 250,000