Covered Assets and FDIC Loss-sharing Asset Covered Loans - Credit Quality Indicator (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Net Reported Amount	$ 2,854,603		$ 2,827,259
Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	554,332		721,313
Valuation discount on covered loans	95,889		184,440
Loans and Leases Receivable, Allowance	29,157	31,784	4,944	8,327	7,948	6,055
Loans and Leases Receivable, Net Reported Amount	429,286		531,929
Covered Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	389,762		454,104
Covered Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	11,648		23,029
Covered Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	152,922		241,261
Covered Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0		2,870
Covered Loans [Member] | Unlikely to be Collected Financing Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0		49
Real Estate Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	320,238		390,636
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	62,959		79,328
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Commercial Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	30,723		44,187
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	119,337		148,919
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	107,219		118,202
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	47,369		56,948
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	17,464		21,947
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	92,829		109,339
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	87,809		89,555
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	1,493		2,210
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		1,213
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	3,337		4,013
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	3,229		3,673
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	14,097		20,170
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	13,259		21,027
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	23,171		35,567
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	16,181		24,974
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	46,468		78,063
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	29,774		54,402
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	13,354		19,364
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	3,340		4,297
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	14,413		25,304
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	15,361		29,098
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	4,702		2,928
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	1,114		1,142
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	4,733		4,834
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	6,504		8,264
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		2,779
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	1,422		1,535
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		371
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	8,652		13,657
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	2,226		3,155
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	8,258		17,646
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	8,857		20,463
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		1,289
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	46,532		56,877
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	40,940		48,067
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	177		255
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	5,415		8,150
Consumer Portfolio Segment [Member] | Covered Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	0		357
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		48
Commercial Portfolio Segment [Member] | Covered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	141,094		195,737
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Secured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	133,915		184,714
Commercial Portfolio Segment [Member] | Covered Loans [Member] | Unsecured Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	7,179		11,023
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	81,399		103,472
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	4,899		7,608
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	1,990		6,239
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		741
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	50,526		73,793
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	2,280		2,659
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		1,209
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		15
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		1
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