USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Offsetting Liabilities (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities		$ 41,240	$ 27,034
Offsetting Financial Liabilities and Derivative Liabilities [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	10,510,908	12,848,968
Gross Amounts Offset in the Balance Sheet		0	529
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	10,510,908	12,849,497
Financial Instruments	[3]	(10,460,193)	(12,814,604)
Cash Collateral Pledged	[3]	(50,499)	(34,893)
Net Amount		216	0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 1 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	28,410	24,533
Gross Amounts Offset in the Balance Sheet		0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	28,410	24,533
Financial Instruments	[3]	0	0
Cash Collateral Pledged	[3]	(28,410)	(24,533)
Net Amount		0	0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 2 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	2,816	4,042
Gross Amounts Offset in the Balance Sheet		0	95
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	2,816	4,137
Financial Instruments	[3]	0	(95)
Cash Collateral Pledged	[3]	(2,600)	(4,042)
Net Amount		216	0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 3 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]		736
Gross Amounts Offset in the Balance Sheet			0
Net Amounts of Liabilities Presented in the Balance Sheet	[2]		736
Financial Instruments	[3]		0
Cash Collateral Pledged	[3]		(736)
Net Amount			0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Counterparty 4 [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	19,489	6,710
Gross Amounts Offset in the Balance Sheet		0	434
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	19,489	7,144
Financial Instruments	[3]	0	(1,562)
Cash Collateral Pledged	[3]	(19,489)	(5,582)
Net Amount		0	0
Offsetting Financial Liabilities and Derivative Liabilities [Member] | Derivative Counterparties [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	50,715	36,021
Gross Amounts Offset in the Balance Sheet		0	529
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	50,715	36,550
Financial Instruments	[3]	0	(1,657)
Cash Collateral Pledged	[3]	(50,499)	(34,893)
Net Amount		216	0
Borrowings under Repurchase Arrangements [Member] | Offsetting Financial Liabilities and Derivative Liabilities [Member]
Offsetting of financial liabilities and derivative liabilities [Abstract]
Gross Amounts of Recognized Liabilities	[1]	10,460,193	12,812,947
Gross Amounts Offset in the Balance Sheet		0	0
Net Amounts of Liabilities Presented in the Balance Sheet	[2]	10,460,193	12,812,947
Financial Instruments	[3]	(10,460,193)	(12,812,947)
Cash Collateral Pledged	[3]	0	0
Net Amount		$ 0	$ 0

[1] Amounts include accrued interest of $9.5 million and $9.5 million on interest rate swap agreements and $8.5 million and $6.1 million on borrowings under repurchase arrangements, included in "Accounts payable and accrued expenses" on the face of the Balance Sheets as of September 30, 2015 and December 31, 2014, respectively.

[2] Amounts presented are limited to recognized liabilities and cash collateral received associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.

[3] Amounts presented are limited to recognized assets and collateral pledged associated with the indicated counterparty sufficient to reduce the related Net Amount to zero in accordance with ASU No. 2011-11, as amended by ASU No. 2013-01.