INVESTMENT SECURITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	$ 2,599,018,000		$ 3,132,968,000
Gross Unrealized Gains	34,739,000		47,356,000
Gross Unrealized Losses	(26,728,000)		(107,746,000)
Fair Value	2,607,029,000		3,072,578,000
Other than temporary impairment, pre-tax basis, credit portion recognized in earnings	99,000		633,000		16,669,000
Other than temporary impairment, pre-tax basis, non-credit portion recognized in other comprehensive income	5,100,000		5,100,000
U.S. Treasury securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	459,613,000		19,892,000
Gross Unrealized Gains	1,135,000		833,000
Gross Unrealized Losses	(71,000)
Fair Value	460,677,000		20,725,000
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		575,148,000
Gross Unrealized Gains	673,000		1,709,000
Gross Unrealized Losses	(82,000)		(279,000)
Fair Value	197,855,000		576,578,000
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		46,008,000
Gross Unrealized Gains	6,665,000		3,307,000
Gross Unrealized Losses	(36,000)
Fair Value	180,665,000		49,315,000
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		963,688,000
Gross Unrealized Gains	20,883,000		30,854,000
Gross Unrealized Losses	(678,000)		(772,000)
Fair Value	1,144,085,000		993,770,000
Municipal securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	163,333,000		76,255,000
Gross Unrealized Gains	4,491,000		3,696,000
Gross Unrealized Losses	(731,000)		(5,000)
Fair Value	167,093,000		79,946,000
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	429,318,000		1,411,409,000
Gross Unrealized Gains	237,000		6,762,000
Gross Unrealized Losses	(17,572,000)		(95,610,000)
Fair Value	411,983,000		1,322,561,000
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	24,620,000	[1]	30,693,000	[1]
Gross Unrealized Gains	355,000	[1]
Gross Unrealized Losses	(7,558,000)	[1]	(11,078,000)	[1]
Fair Value	17,417,000	[1]	19,615,000	[1]
Other securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	9,955,000		9,875,000
Gross Unrealized Gains	215,000		195,000
Gross Unrealized Losses			(2,000)
Fair Value	10,170,000		10,068,000
Other commercial mortgage-backed securities: | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	16,999,000
Gross Unrealized Gains	85,000
Fair Value	$ 17,084,000

[1] For 2012, the Company recorded $99 thousand, on a pre-tax basis, of OTTI through earnings and $5.1 million of the non-credit portion of OTTI for pooled trust securities in other comprehensive income. For 2011, the Company recorded $633 thousand, on a pre-tax basis, of OTTI through earnings and $5.1 million of the non-credit portion of OTTI for pooled trust securities and other mortgage-backed securities in other comprehensive income.