OFFSETTING ASSETS AND LIABILITIES - Schedule of Offsetting Financial Liabilities and Derivative Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Offsetting of derivative liabilities
Gross amounts of recognized liabilities	$ 21,942	$ 13,445
Gross amounts offset in the balance sheet	0	0
Net amount presented in the balance sheet	21,942	13,445
Gross amounts not offset in the balance sheet
Financial instruments	0	0
Cash collateral posted/(received)	21,942	13,445
Net amount	0	0
Offsetting of repurchase agreements
Outstanding Amount	1,191,326	1,431,666
Gross amounts offset in the balance sheet	0	0
Net amount presented in the balance sheet	1,191,326	1,431,666
Gross amounts not offset in the balance sheet
Financial instruments	1,191,326	1,431,666
Cash collateral posted/(received)	0	0
Net amount	0	0
Offsetting of financial liabilities and derivative liabilities
Gross amounts of recognized liabilities	1,213,268	1,445,111
Gross amounts offset in the balance sheet	0	0
Net amount presented in the balance sheet	1,213,268	1,445,111
Gross amounts not offset in the balance sheet
Financial instruments collateral	1,191,326	1,431,666
Cash collateral posted/(received)	21,942	13,445
Net amount	$ 0	$ 0