Covered Assets and FDIC Loss-sharing Asset (Analysis and Allowance for Losses on Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans, net	$ 2,933,306	$ 2,864,803
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	461,852	500,794
Valuation discount on covered loans	69,150	79,401
Allowance for loan losses	29,489	30,056	20,504	4,944
Loans, net	363,213	391,337
Commercial Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	113,876
Real Estate Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [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]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	49,639	57,150
Real Estate Portfolio Segment [Member] | Covered Loans [Member] | Commercial and Multifamily Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	220,037
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [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]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	22,165
Real Estate Construction Portfolio Segment [Member] | Covered Loans [Member] | Commercial and Multifamily Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	14,032
Consumer Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	$ 42,103	$ 44,516