FINANCIAL INSTRUMENTS - Summary of Assets and Liabilities Not Measured At Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financial assets:
Restricted cash	$ 12,448	$ 12,117
Carrying Value
Financial assets:
Cash	115,105	162,374
Restricted cash	12,448	12,117
Loans receivable, net	384,873	363,269
Investment in Cognical	6,600	5,600
Financial liabilities:
Credit services organization guarantee liability	11,619	17,795
Carrying Value | 12% Senior Secured Notes
Financial liabilities:
Senior secured notes	512,136	585,823
Carrying Value | Non-Recourse U.S. SPV Facility
Financial liabilities:
Senior secured notes	114,697	120,402
Estimated Fair Value
Financial assets:
Cash	115,105	162,374
Restricted cash	12,448	12,117
Loans receivable, net	384,873	363,269
Investment in Cognical	6,600	5,600
Financial liabilities:
Credit services organization guarantee liability	11,619	17,795
Estimated Fair Value | 12% Senior Secured Notes
Financial liabilities:
Senior secured notes	553,308	663,475
Estimated Fair Value | Non-Recourse U.S. SPV Facility
Financial liabilities:
Senior secured notes	118,427	124,590
Estimated Fair Value | Level 1
Financial assets:
Cash	115,105	162,374
Restricted cash	12,448	12,117
Loans receivable, net	0	0
Investment in Cognical	0	0
Financial liabilities:
Credit services organization guarantee liability	0	0
Estimated Fair Value | Level 1 | 12% Senior Secured Notes
Financial liabilities:
Senior secured notes	0	0
Estimated Fair Value | Level 1 | Non-Recourse U.S. SPV Facility
Financial liabilities:
Senior secured notes	0	0
Estimated Fair Value | Level 2
Financial assets:
Cash	0	0
Restricted cash	0	0
Loans receivable, net	0	0
Investment in Cognical	0	0
Financial liabilities:
Credit services organization guarantee liability	0	0
Estimated Fair Value | Level 2 | 12% Senior Secured Notes
Financial liabilities:
Senior secured notes	0	0
Estimated Fair Value | Level 2 | Non-Recourse U.S. SPV Facility
Financial liabilities:
Senior secured notes	0	0
Estimated Fair Value | Level 3
Financial assets:
Cash	0	0
Restricted cash	0	0
Loans receivable, net	384,873	363,269
Investment in Cognical	6,600	5,600
Financial liabilities:
Credit services organization guarantee liability	11,619	17,795
Estimated Fair Value | Level 3 | 12% Senior Secured Notes
Financial liabilities:
Senior secured notes	553,308	663,475
Estimated Fair Value | Level 3 | Non-Recourse U.S. SPV Facility
Financial liabilities:
Senior secured notes	$ 118,427	$ 124,590