Covered Assets and FDIC Loss-sharing Asset Covered Loans - Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net Reported Amount	$ 2,933,306	$ 2,864,803
Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	461,852	500,794
Valuation discount on covered loans	69,150	79,401
Loans and Leases Receivable, Allowance	29,489	30,056	20,504	4,944
Loans and Leases Receivable, Net Reported Amount	363,213	391,337
Covered Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	342,697	356,520
Covered Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	8,848	11,003
Covered Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	110,280	133,271
Covered Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	27	0
Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	269,676
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	49,639	57,150
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	25,503	26,628
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	101,541	105,384
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	92,993	101,094
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	40,030	44,782
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	16,047	16,336
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	82,120	81,205
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	76,454	82,222
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	331	1,344
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	3,232	864
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	398	3,318
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	9,278	11,024
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	9,456	10,292
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	16,189	23,315
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	16,141	15,554
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	36,197
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | One-to-Four Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	22,165
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	11,453	12,320
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	2,579	2,931
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	14,137	13,833
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	8,028	11,565
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	4,374	4,419
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	1,099	1,107
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	6,449	4,817
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	2,812	6,050
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	2,796	3,273
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	7,079	7,901
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	1,480	1,824
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	4,892	5,743
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	5,216	5,515
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Income Property Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Land And Acquisition [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Consumer Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	42,103	44,516
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	37,255	38,973
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	419	381
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	4,402	5,162
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	27	0
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Commercial Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	113,876
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	107,703	118,594
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	6,173	6,779
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	71,555	71,621
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	4,502	4,988
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	1,672	1,823
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	34,476	45,150
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	1,671	1,791
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0	0
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	$ 0	$ 0