Noncovered Loans (Analysis of Loan Portfolio by Major Types of Loans) (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, Deferred Income	$ 6,985	$ 7,767
Loans, net	2,933,306	2,864,803
Loans held for sale	888	2,563
Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Deferred Income	6,985	7,767
Recorded Investment	2,621,212	2,525,710
Allowance for loan losses	51,119	52,244	52,283	53,041
Loans, net	2,570,093	2,473,466
Loans held for sale	888	2,563
Commercial Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial and Industrial	1,204,760	1,155,158
Real Estate Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable Real Estate Mortgage	1,150,591	1,105,123
Real Estate Construction Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable Real Estate Construction	120,159	115,703
Consumer Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Consumer	152,687	157,493
Allowance for loan losses	2,364	2,437	2,129	2,719
One-to-Four Family Residential [Member] | Real Estate Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Consumer, Mortgage	43,604	43,922
Allowance for loan losses	657	694	689	654
One-to-Four Family Residential [Member] | Real Estate Construction Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Gross, Consumer, Construction	52,946	50,602
Commercial and Multifamily Residential [Member] | Real Estate Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Mortgage	1,106,987	1,061,201
Commercial and Multifamily Residential [Member] | Real Estate Construction Portfolio Segment [Member] | Noncovered Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans Receivable, Gross, Commercial, Construction	$ 67,213	$ 65,101