LOANS RECEIVABLE AND REVENUE - Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 60,886	$ 71,601	$ 69,568	$ 39,192
Charge-offs	(116,401)	(85,243)	(235,994)	(140,496)
Recoveries	50,861	42,574	104,127	89,776
Net charge-offs	(65,540)	(42,669)	(131,867)	(50,720)
Provision for losses	64,895	40,992	122,516	81,351
Effect of foreign currency translation	(487)	514	(463)	615
Balance, end of period	$ 59,754	$ 70,438	$ 59,754	$ 70,438
Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	13.40%	20.10%	13.40%	20.10%
Consumer Portfolio Segment | Single-Pay
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 4,485	$ 4,719	$ 5,916	$ 5,501
Charge-offs	(44,817)	(44,020)	(92,524)	(88,905)
Recoveries	30,274	30,190	65,283	63,341
Net charge-offs	(14,543)	(13,830)	(27,241)	(25,564)
Provision for losses	14,527	14,284	25,829	25,178
Effect of foreign currency translation	(97)	140	(132)	198
Balance, end of period	$ 4,372	$ 5,313	$ 4,372	$ 5,313
Consumer Portfolio Segment | Single-Pay | Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	4.90%	5.80%	4.90%	5.80%
Consumer Portfolio Segment | Unsecured Installment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 37,916	$ 42,040	$ 43,754	$ 17,775
Charge-offs	(36,102)	(24,574)	(75,479)	(24,574)
Recoveries	6,368	5,716	12,335	10,634
Net charge-offs	(29,734)	(18,858)	(63,144)	(13,940)
Provision for losses	27,434	17,845	54,911	37,154
Effect of foreign currency translation	(337)	379	(242)	417
Balance, end of period	$ 35,279	$ 41,406	$ 35,279	$ 41,406
Consumer Portfolio Segment | Unsecured Installment | Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	19.70%	26.50%	19.70%	26.50%
Consumer Portfolio Segment | Secured Installment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 11,639	$ 20,270	$ 13,472	$ 10,737
Charge-offs	(11,082)	(6,941)	(22,567)	(6,941)
Recoveries	2,296	1,787	5,162	4,815
Net charge-offs	(8,786)	(5,154)	(17,405)	(2,126)
Provision for losses	7,533	4,081	14,319	10,585
Effect of foreign currency translation	0	(1)	0	0
Balance, end of period	$ 10,386	$ 19,196	$ 10,386	$ 19,196
Consumer Portfolio Segment | Secured Installment | Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	12.30%	25.20%	12.30%	25.20%
Consumer Portfolio Segment | Open-End
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 6,846	$ 4,572	$ 6,426	$ 5,179
Charge-offs	(23,807)	(8,447)	(44,156)	(17,676)
Recoveries	11,883	4,104	21,260	9,457
Net charge-offs	(11,924)	(4,343)	(22,896)	(8,219)
Provision for losses	14,848	4,298	26,276	7,563
Effect of foreign currency translation	(53)	(4)	(89)	0
Balance, end of period	$ 9,717	$ 4,523	$ 9,717	$ 4,523
Consumer Portfolio Segment | Open-End | Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	10.70%	16.90%	10.70%	16.90%
Consumer Portfolio Segment | Other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 0	$ 0	$ 0	$ 0
Charge-offs	(593)	(1,261)	(1,268)	(2,400)
Recoveries	40	777	87	1,529
Net charge-offs	(553)	(484)	(1,181)	(871)
Provision for losses	553	484	1,181	871
Effect of foreign currency translation	0	0	0	0
Balance, end of period	$ 0	$ 0	$ 0	$ 0