DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule Of Concentration Of Credit Risk (Details) - Customer Concentration Risk - Revenue Benchmark	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Citadel Securities, LLC
Concentration Risk [Line Items]
Concentration risk, percentage	22.00%	34.00%	29.00%
Tai Mo Shan Limited
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%	0.00%	0.00%
Entities affiliated with Susquehanna International Group, LLP
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	18.00%	13.00%
Entities affiliated with Wolverine Holdings, L.P.
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	10.00%	12.00%
All others individually less than 10%
Concentration Risk [Line Items]
Concentration risk, percentage	18.00%	13.00%	8.00%
Total as percentage of total revenue
Concentration Risk [Line Items]
Concentration risk, percentage	77.00%	75.00%	62.00%