DERIVATIVES (Details 3) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2010	Dec. 31, 2014
Derivatives
Fair value of derivative asset	$ 6,510,000		$ 12,383,000
Fair value of derivative liability	98,748,000		56,493,000
Credit Risk-Related Contingent Feature
Additional collateral required if credit rating is downgraded below investment grade	$ 0		0
Foreign exchange options
Derivatives
Term of contract		5 years
Embedded derivative liabilities
Derivatives
Term of contract	5 years
Derivative instruments not designated as hedging instruments
Derivatives
Notional Amount	$ 6,880,627,000		5,672,472,000
Fair value of derivative asset	96,699,000		55,788,000
Fair value of derivative liability	99,703,000		54,334,000
Derivative instruments not designated as hedging instruments | Foreign exchange options
Derivatives
Notional Amount	0		85,614,000
Fair value of derivative asset	0		6,136,000
Fair value of derivative liability	0		0
Derivative instruments not designated as hedging instruments | Embedded derivative liabilities
Derivatives
Notional Amount	0		47,838,000
Fair value of derivative asset	0		0
Fair value of derivative liability	0		3,392,000
Derivative instruments not designated as hedging instruments | Interest rate swaps and caps
Derivatives
Notional Amount	6,063,494,000		4,858,391,000
Fair value of derivative asset	86,954,000		41,534,000
Fair value of derivative liability	87,330,000		41,779,000
Notional amount of derivative assets	3,000,000,000		2,450,000,000
Notional amount of derivative liabilities	3,060,000,000		2,400,000,000
Derivative instruments not designated as hedging instruments | Short-term foreign exchange contracts
Derivatives
Notional Amount	817,100,000		680,600,000
Fair value of derivative asset	9,700,000		8,100,000
Fair value of derivative liability	$ 12,400,000		$ 9,200,000