Allowance for Noncovered Loan and Lease Losses and Unfunded Commitments and Letters of Credit (Analysis of Credit Quality of Noncovered Loan Portfolio) (Details) (Noncovered Loans [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012 risk_rating	Dec. 31, 2011 risk_rating
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount		$ 2,348,371
Loans and Leases Receivable, Net of Deferred Income	2,371,818	2,348,371
Commercial Portfolio Segment [Member] | Secured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.92	4.89
Loans and Leases Receivable, Gross, Carrying Amount		981,417
Loans and Leases Receivable, Net of Deferred Income	1,028,402
Commercial Portfolio Segment [Member] | Unsecured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.26	4.25
Loans and Leases Receivable, Gross, Carrying Amount		47,406
Loans and Leases Receivable, Net of Deferred Income	47,265
Real Estate Portfolio Segment [Member] | One-to-Four Family Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.76	4.81
Loans and Leases Receivable, Gross, Carrying Amount		64,063
Loans and Leases Receivable, Net of Deferred Income	58,876
Real Estate Portfolio Segment [Member] | Commercial Land [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	5.11	5.22
Loans and Leases Receivable, Gross, Carrying Amount		50,681
Loans and Leases Receivable, Net of Deferred Income	45,380
Real Estate Portfolio Segment [Member] | Income Property Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.00	4.94
Loans and Leases Receivable, Gross, Carrying Amount		533,993
Loans and Leases Receivable, Net of Deferred Income	558,570
Real Estate Portfolio Segment [Member] | Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	5.09	5.05
Loans and Leases Receivable, Gross, Carrying Amount		404,789
Loans and Leases Receivable, Net of Deferred Income	380,196
Real Estate Construction Portfolio Segment [Member] | Income Property Multifamily [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	5.06	5.49
Loans and Leases Receivable, Gross, Carrying Amount		20,877
Loans and Leases Receivable, Net of Deferred Income	19,235
Real Estate Construction Portfolio Segment [Member] | Owner Occupied [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.60	4.55
Loans and Leases Receivable, Gross, Carrying Amount		12,790
Loans and Leases Receivable, Net of Deferred Income	16,008
Real Estate Construction Portfolio Segment [Member] | Land and Acquisition [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	6.29	6.43
Loans and Leases Receivable, Gross, Carrying Amount		25,201
Loans and Leases Receivable, Net of Deferred Income	23,384
Real Estate Construction Portfolio Segment [Member] | Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	5.80	5.94
Loans and Leases Receivable, Gross, Carrying Amount		23,931
Loans and Leases Receivable, Net of Deferred Income	24,480
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Rating	4.22	4.24
Loans and Leases Receivable, Gross, Carrying Amount		183,223
Loans and Leases Receivable, Net of Deferred Income	$ 170,022