INCOME TAXES - Valuation allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance - beginning of year	$ 20,778
Valuation allowance - end of year	16,918	$ 20,778
Operating loss carryforwards
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Change in valuation allowance	(3,422)	661
Foreign tax credit
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Change in valuation allowance	(2,048)	293
U.K. branch assets and other foreign rate differentials
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Change in valuation allowance	1,610	1,264
Income tax expense
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowance - beginning of year	20,778	18,560
Valuation allowance - end of year	$ 16,918	$ 20,778