USE OF DERIVATIVE FINANCIAL INSTRUMENTS, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Changes in AOCI (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	$ 293,910	$ 204,540	$ 173,900
Other comprehensive income (loss) before reclassifications	(91,681)	69,488	2,512
Amounts reclassified from accumulated other comprehensive income	16,914	19,882	28,128
Net other comprehensive income (loss)	(74,767)	89,370	30,640
Ending Balance	219,143	293,910	204,540
Gains and Losses on Cash Flow Hedges [Member]
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	(32,539)	(30,159)	(6,474)
Other comprehensive income (loss) before reclassifications	9,320	(22,262)	(51,751)
Amounts reclassified from accumulated other comprehensive income	16,914	19,882	28,066
Net other comprehensive income (loss)	26,234	(2,380)	(23,685)
Ending Balance	(6,305)	(32,539)	(30,159)
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated other comprehensive income (loss) [Line Items]
Beginning Balance	326,449	234,699	180,374
Other comprehensive income (loss) before reclassifications	(101,001)	91,750	54,263
Amounts reclassified from accumulated other comprehensive income	0	0	62
Net other comprehensive income (loss)	(101,001)	91,750	54,325
Ending Balance	$ 225,448	$ 326,449	$ 234,699