INVESTMENT SECURITIES (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	$ 2,534,163		$ 2,786,490
Gross Unrealized Gains	22,141		12,203
Gross Unrealized Losses	(26,652)		(64,896)
Fair Value	2,529,652		2,733,797
U.S. Treasury securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	450,149		495,053
Gross Unrealized Gains	791		201
Gross Unrealized Losses	(1,628)		(3,622)
Fair Value	449,312		491,632
U.S. government agency and U.S. government sponsored enterprise debt securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	441,747		406,807
Gross Unrealized Gains	938		242
Gross Unrealized Losses	(4,086)		(12,726)
Fair Value	438,599		394,323
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	112,607		182,257
Gross Unrealized Gains	513		1,062
Gross Unrealized Losses	(1,363)		(4,449)
Fair Value	111,757		178,870
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	798,915		892,435
Gross Unrealized Gains	8,108		7,729
Gross Unrealized Losses	(9,057)		(14,927)
Fair Value	797,966		885,237
Municipal securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	289,200		297,390
Gross Unrealized Gains	4,926		1,122
Gross Unrealized Losses	(4,647)		(17,533)
Fair Value	289,479		280,979
Other residential mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	57,065		48,129
Gross Unrealized Gains	557
Gross Unrealized Losses	(416)		(1,802)
Fair Value	57,206		46,327
Other commercial mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	51,000		51,000
Gross Unrealized Gains	463		617
Fair Value	51,463		51,617
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	211,144		312,726
Gross Unrealized Gains	1,172		613
Gross Unrealized Losses	(1,446)		(3,344)
Fair Value	210,870		309,995
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	19,953	[1]	20,668	[1]
Gross Unrealized Gains	131	[1]	62	[1]
Gross Unrealized Losses	(3,505)	[1]	(5,629)	[1]
Fair Value	16,579	[1]	15,101	[1]
Other securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	102,383		80,025
Gross Unrealized Gains	4,542		555
Gross Unrealized Losses	(504)		(864)
Fair Value	$ 106,421		$ 79,716

[1] For the six months ended June 30, 2014 and the year ended December 31, 2013, the Company did not record any OTTI.