SIGNIFICANT ACCOUNTING POLICIES - Schedule of depreciation period for each asset category (Details )	12 Months Ended
	Dec. 31, 2020
Computer equipment and capitalized software | Minimum
Property, Plant and Equipment [Line Items]
Depreciation period	1 year
Computer equipment and capitalized software | Maximum
Property, Plant and Equipment [Line Items]
Depreciation period	5 years
Furniture and other equipment
Property, Plant and Equipment [Line Items]
Depreciation period	7 years
Aircraft and automobile | Minimum
Property, Plant and Equipment [Line Items]
Depreciation period	5 years
Aircraft and automobile | Maximum
Property, Plant and Equipment [Line Items]
Depreciation period	10 years
Software development | Minimum
Property, Plant and Equipment [Line Items]
Depreciation period	1 year
Software development | Maximum
Property, Plant and Equipment [Line Items]
Depreciation period	5 years