Covered Assets and FDIC Loss-sharing Asset (Analysis and Allowance for Losses on Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans, net	$ 2,864,803	$ 2,827,259
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	500,794	721,313
Allowance for losses	30,056	4,944	6,055
Valuation discount resulting from acquisition accounting	79,401	184,440
Loans, net	391,337	531,929
Covered Loans [Member] | Commercial Portfolio Segment [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	125,373	195,737
Covered Loans [Member] | Real Estate Portfolio Segment [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	290,256	390,636
Covered Loans [Member] | Real Estate Portfolio Segment [Member] | One-to-Four Family Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	57,150	79,328
Covered Loans [Member] | Real Estate Portfolio Segment [Member] | Commercial and Multifamily Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	233,106	311,308
Covered Loans [Member] | Real Estate Construction Portfolio Segment [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	40,649	78,063
Covered Loans [Member] | Real Estate Construction Portfolio Segment [Member] | One-to-Four Family Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	25,398	54,402
Covered Loans [Member] | Real Estate Construction Portfolio Segment [Member] | Commercial and Multifamily Residential [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	15,251	23,661
Covered Loans [Member] | Consumer Portfolio Segment [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	$ 44,516	$ 56,877