COVERED ASSETS AND FDIC INDEMNIFICATION ASSET (Details 2) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Credit Quality Indicators
Additional advances under shared-loss agreements	$ 537,200,000
Total allowance allocated to additional advances	8,300,000
Percentage of allowance allocated to additional advances	3.70%
Carrying Amounts And Composition Of Covered Loans
Total principal balance	4,403,108,000	4,718,084,000
Covered discount	(711,142,000)	(788,295,000)
Net valuation of loans	3,691,966,000	3,929,789,000
Allowance on covered loans	(8,268,000)	(6,647,000)
Total covered loans, net	3,683,698,000	3,923,142,000
Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	3,219,910,000	3,439,848,000
Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	115,777,000	146,585,000
Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,055,186,000	1,112,568,000
Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	12,235,000	19,083,000
Real Estate Loans
Carrying Amounts And Composition Of Covered Loans
Total principal balance	3,571,032,000	3,788,478,000
Real Estate Loans | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	2,594,359,000	2,700,389,000
Real Estate Loans | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	75,064,000	111,878,000
Real Estate Loans | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	891,300,000	961,813,000
Real Estate Loans | Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	10,309,000	14,398,000
Real Estate Loans | Residential Single-family
Carrying Amounts And Composition Of Covered Loans
Total principal balance	418,968,000	442,732,000
Real Estate Loans | Residential Single-family | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	405,077,000	427,918,000
Real Estate Loans | Residential Single-family | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,487,000	1,085,000
Real Estate Loans | Residential Single-family | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	12,404,000	13,729,000
Real Estate Loans | Residential Multifamily
Carrying Amounts And Composition Of Covered Loans
Total principal balance	882,656,000	918,941,000
Real Estate Loans | Residential Multifamily | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	751,603,000	779,694,000
Real Estate Loans | Residential Multifamily | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	24,128,000	26,124,000
Real Estate Loans | Residential Multifamily | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	106,925,000	113,123,000
Real Estate Loans | Commercial and Industrial Real Estate
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,692,719,000	1,773,760,000
Real Estate Loans | Commercial and Industrial Real Estate | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,203,273,000	1,249,781,000
Real Estate Loans | Commercial and Industrial Real Estate | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	7,735,000	43,810,000
Real Estate Loans | Commercial and Industrial Real Estate | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	474,076,000	472,003,000
Real Estate Loans | Commercial and Industrial Real Estate | Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	7,635,000	8,166,000
Real Estate Loans | Construction and Land
Carrying Amounts And Composition Of Covered Loans
Total principal balance	576,689,000	653,045,000
Real Estate Loans | Construction and Land | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	234,406,000	242,996,000
Real Estate Loans | Construction and Land | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	41,714,000	40,859,000
Real Estate Loans | Construction and Land | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	297,895,000	362,958,000
Real Estate Loans | Construction and Land | Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	2,674,000	6,232,000
Other Loans
Carrying Amounts And Composition Of Covered Loans
Total principal balance	832,076,000	929,606,000
Other Loans | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	625,551,000	739,459,000
Other Loans | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	40,713,000	34,707,000
Other Loans | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	163,886,000	150,755,000
Other Loans | Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,926,000	4,685,000
Other Loans | Commercial Business
Carrying Amounts And Composition Of Covered Loans
Total principal balance	735,479,000	831,762,000
Other Loans | Commercial Business | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	531,311,000	643,117,000
Other Loans | Commercial Business | Special Mention
Carrying Amounts And Composition Of Covered Loans
Total principal balance	40,713,000	34,707,000
Other Loans | Commercial Business | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	161,529,000	149,253,000
Other Loans | Commercial Business | Doubtful
Carrying Amounts And Composition Of Covered Loans
Total principal balance	1,926,000	4,685,000
Other Loans | Other Consumer
Carrying Amounts And Composition Of Covered Loans
Total principal balance	96,597,000	97,844,000
Other Loans | Other Consumer | Pass/Watch
Carrying Amounts And Composition Of Covered Loans
Total principal balance	94,240,000	96,342,000
Other Loans | Other Consumer | Substandard
Carrying Amounts And Composition Of Covered Loans
Total principal balance	2,357,000	1,502,000
Residential
Credit Quality Indicators
Additional advances under shared-loss agreements	12,200,000
Total allowance allocated to additional advances	133,000
Commercial Real Estate ("CRE")
Credit Quality Indicators
Additional advances under shared-loss agreements	145,100,000
Total allowance allocated to additional advances	5,200,000
Commercial and Industrial ("C&I")
Credit Quality Indicators
Additional advances under shared-loss agreements	346,200,000
Total allowance allocated to additional advances	2,800,000
Consumer
Credit Quality Indicators
Additional advances under shared-loss agreements	33,700,000
Total allowance allocated to additional advances	$ 182,000