NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Allowance for Loan Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended				12 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010		Dec. 31, 2010
Covered Loans [Abstract]
Percentage of total general reserve for allowance for loan losses allocated to covered loans (in hundredths)	2.90%			2.90%				1.80%
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 220,556			$ 234,633		$ 238,833		$ 238,833
Provision for loan losses	22,000		38,648	75,006		170,325		200,159
Allowance for unfunded loan commitments and letters of credit	0			(1,245)				(1,833)
Charge-offs	(27,575)			(100,705)				(225,203)
Recoveries	3,191			10,483				22,677
Net charge-offs	(24,384)			(90,222)				(202,526)
Ending balance	218,172			218,172				234,633
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	8,474			8,474				10,024
Loans collectively evaluated for impairment	209,698			209,698				224,609
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	218,172			218,172				234,633
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	44,630			49,491		38,025		38,025
Provision for loan losses	7,172			7,618				59,525
Allowance for unfunded loan commitments and letters of credit	0			0				0
Charge-offs	(3,835)			(9,388)				(49,685)
Recoveries	203			449				1,626
Net charge-offs	(3,632)			(8,939)				(48,059)
Ending balance	48,170			48,170				49,491
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	1,484			1,484				309
Loans collectively evaluated for impairment	46,686			46,686				49,182
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	48,170			48,170				49,491
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	85,686			117,752		147,591		147,591
Provision for loan losses	1,193			10,861				97,548
Allowance for unfunded loan commitments and letters of credit	0							0
Charge-offs	(15,863)			(60,248)				(137,460)
Recoveries	1,851			4,502				10,073
Net charge-offs	(14,012)			(55,746)				(127,387)
Ending balance	72,867			72,867				117,752
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	4,843			4,843				7,247
Loans collectively evaluated for impairment	68,024			68,024				110,505
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	72,867			72,867				117,752
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	79,985			59,737		50,487		50,487
Provision for loan losses	13,471			51,223				34,613
Allowance for unfunded loan commitments and letters of credit	0			0				0
Charge-offs	(7,602)			(29,410)				(35,479)
Recoveries	1,115			5,419				10,116
Net charge-offs	(6,487)			(23,991)				(25,363)
Ending balance	86,969			86,969				59,737
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	2,147			2,147				2,468
Loans collectively evaluated for impairment	84,822			84,822				57,269
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	86,969			86,969				59,737
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	3,524			3,428		2,730		2,730
Provision for loan losses	461			1,850				2,415
Allowance for unfunded loan commitments and letters of credit	0			0				0
Charge-offs	(275)			(1,659)				(2,579)
Recoveries	22			113				862
Net charge-offs	(253)			(1,546)				(1,717)
Ending balance	3,732			3,732				3,428
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	0			0				0
Loans collectively evaluated for impairment	3,732			3,732				3,428
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	3,732			3,732				3,428
Covered Loans Subject to Allowance For Loan Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	6,731	[2]		4,225	[2]	0	[2]	0	[2]
Provision for loan losses	(297)	[2]		2,209	[2]			4,225	[2]
Allowance for unfunded loan commitments and letters of credit	0	[2]		0	[2]			0	[2]
Charge-offs	0	[2]		0	[2]			0	[2]
Recoveries	0	[2]		0	[2]			0	[2]
Net charge-offs	0	[2]		0	[2]			0	[2]
Ending balance	6,434	[2]		6,434	[2]			4,225	[2]
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	0	[2]		0	[2]			0	[2]
Loans collectively evaluated for impairment	6,434	[2]		6,434	[2]			4,225	[2]
Loans acquired with deteriorated credit quality	0	[1],[2]		0	[1],[2]			0	[1],[2]
Ending balance	6,434	[2]		6,434	[2]			4,225	[2]
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	0			0		0		0
Provision for loan losses	0			1,245				1,833
Allowance for unfunded loan commitments and letters of credit	0			(1,245)				(1,833)
Charge-offs	0			0				0
Recoveries	0			0				0
Net charge-offs	0			0				0
Ending balance	0			0				0
Ending balance allocated to: [Abstract]
Loans individually evaluated for impairment	0			0				0
Loans collectively evaluated for impairment	0			0				0
Loans acquired with deteriorated credit quality	0	[1]		0	[1]			0	[1]
Ending balance	$ 0			$ 0				$ 0

[1] The Company has elected to account for all covered loans acquired in the FDIC-assisted acquisitions under ASC 310-30.

[2] This allowance is related to drawdowns on commitments that were in existence as of the acquisition dates of WFIB and UCB and, therefore, are covered under the shared-loss agreements with the FDIC. Allowance on these subsequent drawdowns is accounted for as part of the allowance for loan losses.