INVESTMENT SECURITIES (Gross Unrealized Loss and Fair Value of Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 1,007,943	$ 6,182,194
12 months or longer, Fair Value	5,249,334	1,023,099
Total, Fair Value	6,257,277	7,205,293
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(6,825)	(307,072)
12 months or longer, Unrealized Losses	(212,176)	(83,846)
Total, Unrealized Losses	(219,001)	(390,918)
Corporate debt securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	67,225	743,041
12 months or longer, Fair Value	216,573	32,020
Total, Fair Value	283,798	775,061
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(129)	(10,868)
12 months or longer, Unrealized Losses	(2,711)	(1,567)
Total, Unrealized Losses	(2,840)	(12,435)
Asset-backed securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	576,287	803,685
12 months or longer, Fair Value	95,495	24,316
Total, Fair Value	671,782	828,001
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(2,534)	(4,111)
12 months or longer, Unrealized Losses	(618)	(239)
Total, Unrealized Losses	(3,152)	(4,350)
Equity securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	30	5,020
12 months or longer, Fair Value	9,854	4,797
Total, Fair Value	9,884	9,817
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	0	(188)
12 months or longer, Unrealized Losses	(312)	(302)
Total, Unrealized Losses	(312)	(490)
State and municipal securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	103,244	710,456
12 months or longer, Fair Value	514,405	126,345
Total, Fair Value	617,649	836,801
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(345)	(45,972)
12 months or longer, Unrealized Losses	(12,904)	(16,390)
Total, Unrealized Losses	(13,249)	(62,362)
Mortgage-backed securities, U.S. government agencies [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	98,283	1,648,691
12 months or longer, Fair Value	1,677,833	139,791
Total, Fair Value	1,776,116	1,788,482
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(205)	(94,937)
12 months or longer, Unrealized Losses	(44,720)	(8,952)
Total, Unrealized Losses	(44,925)	(103,889)
Mortgage-backed securities, FHLMC and FNMA debt securities [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, Fair Value	162,874	2,271,301
12 months or longer, Fair Value	2,735,174	695,830
Total, Fair Value	2,898,048	2,967,131
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Less than 12 months, Unrealized Losses	(3,612)	(150,996)
12 months or longer, Unrealized Losses	(150,911)	(56,396)
Total, Unrealized Losses	$ (154,523)	$ (207,392)