FAIR VALUE DISCLOSURES - Summary of Financial Assets and Liabilities Measure at Fair Value on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Assets
Derivatives	$ 14,848	$ 24,135
Available-for-sale investment securities	854,747	1,032,096
Liabilities
Derivatives	16,044	26,423
Fair Value, Measurements, Recurring
Assets
Derivatives	0	0
Available-for-sale investment securities	854,747	1,032,096
Total	854,747	1,032,096
Liabilities
Derivatives	1,196	2,517
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 1
Assets
Derivatives	0	0
Available-for-sale investment securities	185	144
Total	185	144
Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 2
Assets
Derivatives	14,848	24,135
Available-for-sale investment securities	854,562	1,031,952
Total	869,410	1,056,087
Liabilities
Derivatives	16,044	26,652
Fair Value, Measurements, Recurring | Fair Value Measurements Using Level 3
Assets
Derivatives	0	0
Available-for-sale investment securities	0	0
Total	0	0
Liabilities
Derivatives	0	0
Fair Value, Measurements, Recurring | Netting Adjustments
Assets
Derivatives	(14,848)	(24,135)
Available-for-sale investment securities	0	0
Total	(14,848)	(24,135)
Liabilities
Derivatives	$ (14,848)	$ (24,135)