INVESTMENT SECURITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2013
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	$ 2,599,018,000			$ 2,786,490,000
Gross Unrealized Gains	34,739,000			12,203,000
Gross Unrealized Losses	(26,728,000)			(64,896,000)
Fair Value	2,607,029,000			2,733,797,000
Other than temporary impairment, pre-tax basis, credit portion recognized in earnings	99,000		633,000
Other than temporary impairment, pre-tax basis, non-credit portion recognized in other comprehensive income	5,100,000
U.S. Treasury securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	459,613,000			495,053,000
Gross Unrealized Gains	1,135,000			201,000
Gross Unrealized Losses	(71,000)			(3,622,000)
Fair Value	460,677,000			491,632,000
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	197,264,000			406,807,000
Gross Unrealized Gains	673,000			242,000
Gross Unrealized Losses	(82,000)			(12,726,000)
Fair Value	197,855,000			394,323,000
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	174,036,000			182,257,000
Gross Unrealized Gains	6,665,000			1,062,000
Gross Unrealized Losses	(36,000)			(4,449,000)
Fair Value	180,665,000			178,870,000
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	1,123,880,000			892,435,000
Gross Unrealized Gains	20,883,000			7,729,000
Gross Unrealized Losses	(678,000)			(14,927,000)
Fair Value	1,144,085,000			885,237,000
Municipal securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	163,333,000			297,390,000
Gross Unrealized Gains	4,491,000			1,122,000
Gross Unrealized Losses	(731,000)			(17,533,000)
Fair Value	167,093,000			280,979,000
Other residential mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost				48,129,000
Gross Unrealized Losses				(1,802,000)
Fair Value				46,327,000
Other commercial mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	16,999,000			51,000,000
Gross Unrealized Gains	85,000			617,000
Fair Value	17,084,000			51,617,000
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	429,318,000			312,726,000
Gross Unrealized Gains	237,000			613,000
Gross Unrealized Losses	(17,572,000)			(3,344,000)
Fair Value	411,983,000			309,995,000
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	24,620,000	[1]		20,668,000	[1]
Gross Unrealized Gains	355,000	[1]		62,000	[1]
Gross Unrealized Losses	(7,558,000)	[1]		(5,629,000)	[1]
Fair Value	17,417,000	[1]		15,101,000	[1]
Other securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	9,955,000			80,025,000
Gross Unrealized Gains	215,000			555,000
Gross Unrealized Losses				(864,000)
Fair Value	$ 10,170,000			$ 79,716,000

[1] For 2013, the Company did not record any OTTI. For 2012, the Company recorded $99 thousand, on a pre-tax basis, of the credit portion of OTTI through earnings and $5.1 million of the non-credit portion of OTTI for pooled trust preferred securities in other comprehensive income.