SEGMENT REPORTING - Summary of Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 261,758	$ 224,580
Gross margin	109,245	94,905
Expenditures for long-lived assets by segment	1,609	3,093
Gross loans receivable	389,838		$ 432,837
U.S.
Segment Reporting Information [Line Items]
Revenue	204,593	174,322
Gross margin	91,344	77,133
Expenditures for long-lived assets by segment	788	1,672
Gross loans receivable	266,731		308,696
Canada
Segment Reporting Information [Line Items]
Revenue	46,250	41,566
Gross margin	14,502	14,300
Expenditures for long-lived assets by segment	754	1,291
Gross loans receivable	102,597		104,551
U.K.
Segment Reporting Information [Line Items]
Revenue	10,915	8,692
Gross margin	3,399	3,472
Expenditures for long-lived assets by segment	67	$ 130
Gross loans receivable	$ 20,510		$ 19,590

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.1-5)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.10(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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