LOANS RECEIVABLE AND REVENUE - Allowance for loan losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 69,568	$ 39,194
Charge-offs	(119,593)	(55,253)
Recoveries	53,266	47,200
Net charge-offs	(66,327)	(8,053)
Provision for losses	57,621	40,359
Effect of foreign currency translation	24	101
Balance, end of period	$ 60,886	$ 71,601
Allowance for Losses on Finance Receivables | Credit Concentration Risk
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Concentration risk, percentage	15.60%	23.50%
Consumer Portfolio Segment | Single-Pay
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 5,916	$ 5,425
Charge-offs	(47,707)	(44,885)
Recoveries	35,009	33,227
Net charge-offs	(12,698)	(11,658)
Provision for losses	11,302	10,894
Effect of foreign currency translation	(35)	58
Balance, end of period	$ 4,485	$ 4,719
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	5.20%	5.90%
Consumer Portfolio Segment | Unsecured Installment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 43,754	$ 17,853
Charge-offs	(39,377)	0
Recoveries	5,967	4,840
Net charge-offs	(33,410)	4,840
Provision for losses	27,477	19,309
Effect of foreign currency translation	95	38
Balance, end of period	$ 37,916	$ 42,040
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	22.10%	32.00%
Consumer Portfolio Segment | Secured Installment
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 13,472	$ 10,737
Charge-offs	(11,485)	0
Recoveries	2,866	3,028
Net charge-offs	(8,619)	3,028
Provision for losses	6,786	6,504
Effect of foreign currency translation	0	1
Balance, end of period	$ 11,639	$ 20,270
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	14.60%	30.00%
Consumer Portfolio Segment | Open-End
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 6,426	$ 5,179
Charge-offs	(20,349)	(9,229)
Recoveries	9,377	5,353
Net charge-offs	(10,972)	(3,876)
Provision for losses	11,428	3,265
Effect of foreign currency translation	(36)	4
Balance, end of period	$ 6,846	$ 4,572
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	13.30%	17.80%
Consumer Portfolio Segment | Other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 0	$ 0
Charge-offs	(675)	(1,139)
Recoveries	47	752
Net charge-offs	(628)	(387)
Provision for losses	628	387
Effect of foreign currency translation	0	0
Balance, end of period	$ 0	$ 0