INVESTMENTS IN CONSUMER LOANS - Others' Interest in Equity of Consumer Loan Companies (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Noncontrolling Interest [Line Items]
Total Consumer Loan Companies equity	$ 5,997,670				$ 4,690,205				$ 5,997,670	$ 4,690,205
Noncontrolling interests in equity of consolidated subsidiaries	90,625				105,957				90,625	105,957
Noncontrolling Interests in Income of Consolidated Subsidiaries	8,506	$ 10,869	$ 11,078	$ 10,111	12,068	$ 13,600	$ 15,671	$ 15,780	40,564	57,119	$ 78,263
Consumer Loan Companies
Noncontrolling Interest [Line Items]
Total Consumer Loan Companies equity	66,105				74,071				66,105	74,071
Net Consumer Loan Companies income (loss)									79,539	98,692
Consumer Loan Companies
Noncontrolling Interest [Line Items]
Noncontrolling interests in equity of consolidated subsidiaries	$ 30,561				$ 34,466				30,561	34,466
Noncontrolling Interests in Income of Consolidated Subsidiaries									$ 36,987	$ 45,892
Other's Interest | Consumer Loan Companies
Noncontrolling Interest [Line Items]
Others’ ownership interest	46.50%				46.50%				46.50%	46.50%