STOCK-BASED COMPENSATION - Summary of Common Stock Option Activity (Details) $ / shares in Units, $ in Thousands		6 Months Ended
Jan. 01, 2019 shares	Jun. 30, 2021 USD ($) $ / shares shares
Shares (in thousands)
Beginning balance (in shares)		513,000
Granted (in shares)		0
Exercised (in shares)		(80,000)
Forfeited (in shares)		0
Canceled (in shares)		0
Ending balance (in shares)		433,000
Weighted-Average Exercise Price
Beginning balance (in usd per share) \| $ / shares		$ 23.91
Granted (in usd per share) \| $ / shares		0
Exercised (in usd per share) \| $ / shares		18.11
Forfeited (in usd per share) \| $ / shares		0
Canceled (in usd per share) \| $ / shares		0
Ending balance (in usd per share) \| $ / shares		$ 24.99
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value \| $		$ 44,115
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		431,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price \| $ / shares		$ 24.99
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,393,040
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value \| $		$ 7,768
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $		$ 43,971
Common stock options
Weighted-Average Exercise Price
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		5 years 4 months 2 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		5 years 4 months 2 days
Common Stock Options From Dosh Acquisition
Shares (in thousands)
Beginning balance (in shares)		0
Assumed (in shares)		104,000
Exercised (in shares)		(4,000)
Forfeited (in shares)		(29,000)
Canceled (in shares)		0
Ending balance (in shares)		71,000
Weighted-Average Exercise Price
Beginning balance (in usd per share) \| $ / shares		$ 0
Assumed (in usd per share) \| $ / shares		3.06
Exercised (in usd per share) \| $ / shares		3.06
Forfeited (in usd per share) \| $ / shares		3.06
Canceled (in usd per share) \| $ / shares		0
Ending balance (in usd per share) \| $ / shares		$ 3.06
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		8 years 3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value \| $		$ 8,801
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		12,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price \| $ / shares		$ 3.06
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		7 years 6 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $		$ 1,444

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Number of options outstanding, including both vested and non-vested options.

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