INVESTMENT SECURITIES (Details 5) (USD $)				9 Months Ended							9 Months Ended
	Sep. 30, 2012 item	Dec. 31, 2011	Sep. 30, 2012 Residential mortgage-backed securities item	Sep. 30, 2012 Corporate debt securities	Sep. 30, 2012 Corporate debt securities Investment grade item	Dec. 31, 2011 Corporate debt securities Investment grade	Sep. 30, 2012 Corporate debt securities Non-investment grade		Dec. 31, 2011 Corporate debt securities Non-investment grade		Sep. 30, 2012 Trust Preferred Securities item	Sep. 30, 2012 U.S. Treasury securities item	Dec. 31, 2011 U.S. Treasury securities	Sep. 30, 2012 Municipal securities item	Dec. 31, 2011 Municipal securities	Sep. 30, 2012 Other securities item	Dec. 31, 2011 Other securities
Schedule of Available-for-sale Securities
Fair value of available for sale securities	$ 2,237,848,000	$ 3,072,578,000			$ 412,719,000	$ 1,322,561,000	$ 13,610,000	[1]	$ 19,615,000	[1]		$ 400,032,000	$ 20,725,000	$ 113,597,000	$ 79,946,000	$ 10,122,000	$ 10,068,000
Continuous unrealized loss position 12 months or more, fair value	326,664,000	359,776,000			315,533,000	350,181,000	11,131,000		9,595,000		11,100,000
Total investment securities available-for-sale portfolio (as a percent)					18.00%						1.00%
Number of securities in a continuous unrealized loss position for more than twelve months	19				14						5
Number of individual securities with a continuous unrealized loss position less than 12 months	20		10		4							3		2		1
Percentage of total amortized cost basis of these securities							45.00%
Gross unrealized losses in loss position twelve months or more	(33,258,000)	(44,188,000)			(24,256,000)	(33,675,000)	(9,002,000)		(10,513,000)
Gross unrealized losses, trust preferred securities, portion representing impairment loss on securities not other-than-temporarily-impaired							3,900,000
Gross unrealized losses, trust preferred securities, portion representing non-credit impairment loss on securities other-than-temporarily-impaired							5,100,000
Impairment loss relating to additional increases to the amount related to the credit loss for which an other-than-temporary impairment was previously recognized											99,000
Decrease in corporate debt securities				$ 915,800,000

[1] For the nine months ended September 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.