FAIR VALUE MEASUREMENTS - Summary of Assets and Liabilities Measured and Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Aug. 31, 2018
Financial assets:
Restricted cash	$ 69,299	$ 54,765	$ 63,274
Financial liabilities:
Contingent consideration related to acquisition	$ 21,239	$ 0
8.25% Senior Secured Notes | Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate	8.25%	8.25%		8.25%
Fair Value, Measurements, Recurring | Measurement period adjustments
Financial assets:
Cash Surrender Value of Life Insurance	$ 7,838	$ 7,140
Financial liabilities:
Non-qualified deferred compensation plan	4,854	4,690
Contingent consideration related to acquisition	21,239
Fair Value, Measurements, Recurring | Estimated Fair Value
Financial assets:
Cash Surrender Value of Life Insurance	7,838	7,140
Financial liabilities:
Non-qualified deferred compensation plan	4,854	4,690
Contingent consideration related to acquisition	21,239
Fair Value, Measurements, Recurring | Estimated Fair Value | Level 1
Financial assets:
Cash Surrender Value of Life Insurance	7,838	7,140
Financial liabilities:
Non-qualified deferred compensation plan	4,854	4,690
Contingent consideration related to acquisition	0
Fair Value, Measurements, Recurring | Estimated Fair Value | Level 2
Financial assets:
Cash Surrender Value of Life Insurance	0	0
Financial liabilities:
Non-qualified deferred compensation plan	0	0
Contingent consideration related to acquisition	0
Fair Value, Measurements, Recurring | Estimated Fair Value | Level 3
Financial assets:
Cash Surrender Value of Life Insurance	0	0
Financial liabilities:
Non-qualified deferred compensation plan	0	0
Contingent consideration related to acquisition	21,239
Fair Value, Measurements, Nonrecurring | Measurement period adjustments
Financial assets:
Cash and cash equivalents	276,367	213,343
Restricted cash	69,299	54,765
Loans receivable, net	701,367	467,560
Financial liabilities:
Liability for losses on CSO lender-owned consumer loans	5,265	7,228
Fair Value, Measurements, Nonrecurring | Measurement period adjustments | 8.25% Senior Secured Notes | Senior Notes
Financial liabilities:
Debt	680,893	680,000
Fair Value, Measurements, Nonrecurring | Measurement period adjustments | Non-Recourse U.S. SPV facility
Financial liabilities:
Debt	44,489	43,586
Fair Value, Measurements, Nonrecurring | Measurement period adjustments | Non-Recourse Canada SPV facility
Financial liabilities:
Debt	98,881	96,075
Fair Value, Measurements, Nonrecurring | Measurement period adjustments | Non-Recourse Flexiti SPE facility
Financial liabilities:
Debt	194,864
Fair Value, Measurements, Nonrecurring | Estimated Fair Value
Financial assets:
Cash and cash equivalents	276,367	213,343
Restricted cash	69,299	54,765
Loans receivable, net	701,367	467,560
Financial liabilities:
Liability for losses on CSO lender-owned consumer loans	5,265	7,228
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | 8.25% Senior Secured Notes | Senior Notes
Financial liabilities:
Debt	714,150	646,000
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Non-Recourse U.S. SPV facility
Financial liabilities:
Debt	49,456	49,456
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Non-Recourse Canada SPV facility
Financial liabilities:
Debt	100,209	97,971
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Non-Recourse Flexiti SPE facility
Financial liabilities:
Debt	199,646
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	276,367	213,343
Restricted cash	69,299	54,765
Loans receivable, net	0	0
Financial liabilities:
Liability for losses on CSO lender-owned consumer loans	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 1 | 8.25% Senior Secured Notes | Senior Notes
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 1 | Non-Recourse U.S. SPV facility
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 1 | Non-Recourse Canada SPV facility
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 1 | Non-Recourse Flexiti SPE facility
Financial liabilities:
Debt	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 2
Financial assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Loans receivable, net	0	0
Financial liabilities:
Liability for losses on CSO lender-owned consumer loans	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 2 | 8.25% Senior Secured Notes | Senior Notes
Financial liabilities:
Debt	714,150	646,000
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 2 | Non-Recourse U.S. SPV facility
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 2 | Non-Recourse Canada SPV facility
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 2 | Non-Recourse Flexiti SPE facility
Financial liabilities:
Debt	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 3
Financial assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Loans receivable, net	701,367	467,560
Financial liabilities:
Liability for losses on CSO lender-owned consumer loans	5,265	7,228
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 3 | 8.25% Senior Secured Notes | Senior Notes
Financial liabilities:
Debt	0	0
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 3 | Non-Recourse U.S. SPV facility
Financial liabilities:
Debt	49,456	49,456
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 3 | Non-Recourse Canada SPV facility
Financial liabilities:
Debt	100,209	$ 97,971
Fair Value, Measurements, Nonrecurring | Estimated Fair Value | Level 3 | Non-Recourse Flexiti SPE facility
Financial liabilities:
Debt	$ 199,646