FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Investments in securities:
Trading	$ 46,195	$ 79,620
Contingent consideration	(9,257)
Fair Value, Net Asset (Liability)	36,938	79,620
Level 1
Investments in securities:
Trading	42,785	77,327
Contingent consideration	0
Fair Value, Net Asset (Liability)	42,785	77,327
Level 2
Investments in securities:
Trading	3,410	2,293
Contingent consideration	0
Fair Value, Net Asset (Liability)	3,410	2,293
Level 3
Investments in securities:
Trading	0	0
Contingent consideration	(9,257)
Fair Value, Net Asset (Liability)	$ (9,257)	$ 0