RETIREMENT FUND AND PROFIT SHARING PLAN, Employees' Savings Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
UNITED STATES | Class A Common Stock [Member]
Compensation Expense [Abstract]
Shares owned by plan (in shares)	133,280		133,280
UNITED STATES | Class B Common Stock [Member]
Compensation Expense [Abstract]
Shares owned by plan (in shares)	107,962		107,962
401K Plan [Member] | UNITED STATES
Compensation Expense [Abstract]
Compensation expense	$ 300	$ 300	$ 600	$ 600
Retirement Fund [Member] | HONG KONG
Compensation Expense [Abstract]
Compensation expense	$ 100	$ 100	$ 200	$ 200
Retirement Fund [Member] | HONG KONG | Class A Common Stock [Member]
Compensation Expense [Abstract]
Shares owned by plan (in shares)	3,323		3,323
Retirement Fund [Member] | HONG KONG | Class B Common Stock [Member]
Compensation Expense [Abstract]
Shares owned by plan (in shares)	17,342		17,342