NON-COVERED LOANS AND ALLOWANCE FOR LOAN LOSSES (Details 7) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Covered loans
Percentage of total general reserve for allowance for loan losses allocated to covered loans	3.70%				3.10%
Allowance on covered loans	$ (8,268)				$ (6,647)
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	216,523		234,633		234,633
Provision for loan losses	18,100		26,506		95,006
Allowance for unfunded loan commitments and letters of credit	(1,778)				(1,048)
Charge-offs	(16,788)				(124,691)
Recoveries	6,464				12,623
Net charge-offs	(10,324)		(34,200)		(112,068)
Ending balance	222,521				216,523
Ending balance allocated to:
Loans individually evaluated for impairment	5,952				13,041
Loans collectively evaluated for impairment	216,569				203,482
Ending balance	222,521				216,523
Residential
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	52,180		49,491		49,491
Provision for loan losses	1,103				15,416
Charge-offs	(3,031)				(13,323)
Recoveries	941				596
Net charge-offs	(2,090)				(12,727)
Ending balance	51,193				52,180
Ending balance allocated to:
Loans individually evaluated for impairment	683				2,255
Loans collectively evaluated for impairment	50,510				49,925
Ending balance	51,193				52,180
Commercial Real Estate ("CRE")
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	66,457		117,752		117,752
Provision for loan losses	12,465				22,817
Charge-offs	(10,707)				(78,803)
Recoveries	2,775				4,691
Net charge-offs	(7,932)				(74,112)
Ending balance	70,990				66,457
Ending balance allocated to:
Loans individually evaluated for impairment	3,300				5,951
Loans collectively evaluated for impairment	67,690				60,506
Ending balance	70,990				66,457
Commercial and Industrial ("C&I")
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	87,020		59,737		59,737
Provision for loan losses	1,315				50,848
Charge-offs	(2,887)				(30,606)
Recoveries	2,665				7,041
Net charge-offs	(222)				(23,565)
Ending balance	88,113				87,020
Ending balance allocated to:
Loans individually evaluated for impairment	1,969				4,835
Loans collectively evaluated for impairment	86,144				82,185
Ending balance	88,113				87,020
Consumer
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	4,219		3,428		3,428
Provision for loan losses	(182)				2,455
Charge-offs	(163)				(1,959)
Recoveries	83				295
Net charge-offs	(80)				(1,664)
Ending balance	3,957				4,219
Ending balance allocated to:
Loans collectively evaluated for impairment	3,957				4,219
Ending balance	3,957				4,219
Covered Loans Subject to Allowance For Loan Losses
Financing Receivable Allowance for Credit Losses Roll Forward
Beginning balance	6,647	[1]	4,225	[1]	4,225	[1]
Provision for loan losses	1,621	[1]			2,422	[1]
Ending balance	8,268	[1]			6,647	[1]
Ending balance allocated to:
Loans collectively evaluated for impairment	8,268	[1]			6,647	[1]
Ending balance	8,268	[1]			6,647	[1]
Unallocated
Financing Receivable Allowance for Credit Losses Roll Forward
Provision for loan losses	1,778				1,048
Allowance for unfunded loan commitments and letters of credit	$ (1,778)				$ (1,048)

[1] 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.