INVESTMENT SECURITIES (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended			12 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Dec. 31, 2011
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	$ 1,902,789			$ 3,132,968
Gross Unrealized Gains	28,693			47,356
Gross Unrealized Losses	(57,743)			(107,746)
Fair Value	1,873,739			3,072,578
Other than temporary impairment, pre-tax basis, credit portion recognized in earnings	99			633
Other than temporary impairment, pre-tax basis, non-credit portion recognized in other comprehensive income	5,066		5,091	5,100
U.S. Treasury securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	71,509			19,892
Gross Unrealized Gains	704			833
Gross Unrealized Losses	(25)
Fair Value	72,188			20,725
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	359,424			575,148
Gross Unrealized Gains	374			1,709
Gross Unrealized Losses	(74)			(279)
Fair Value	359,724			576,578
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	44,702			46,008
Gross Unrealized Gains	3,987			3,307
Fair Value	48,689			49,315
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	856,734			963,688
Gross Unrealized Gains	19,969			30,854
Gross Unrealized Losses	(459)			(772)
Fair Value	876,244			993,770
Municipal securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	62,652			76,255
Gross Unrealized Gains	3,160			3,696
Gross Unrealized Losses	(30)			(5)
Fair Value	65,782			79,946
Corporate debt securities | Investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	473,187			1,411,409
Gross Unrealized Gains	245			6,762
Gross Unrealized Losses	(47,377)			(95,610)
Fair Value	426,055			1,322,561
Corporate debt securities | Non-investment grade
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	24,665	[1]		30,693	[1]
Gross Unrealized Gains	32	[1]
Gross Unrealized Losses	(9,778)	[1]		(11,078)	[1]
Fair Value	14,919	[1]		19,615	[1]
Other securities
Schedule of Available-for-sale Securities
Investment securities available-for-sale, amortized cost	9,916			9,875
Gross Unrealized Gains	222			195
Gross Unrealized Losses				(2)
Fair Value	$ 10,138			$ 10,068

[1] For the six months ended June 30, 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. The Company recorded $633 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 and other mortgage-backed securities in other comprehensive income for the year ended December 31, 2011.