Covered Assets and FDIC Loss-sharing Asset (Analysis of Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans, net	$ 4,440,048		$ 2,864,803
Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	374,342		500,794
Valuation discount on covered loans	49,445		79,401
Allowance for loan losses	22,737	26,135	30,056	29,157	31,784	4,944
Loans, net	302,160		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	87,366		125,373
Real Estate Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	226,600		290,256
One-to-Four Family Residential Construction [Domain] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	16,018		25,398
Commercial and Multifamily Residential Construction [Domain] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	7,146		15,251
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	23,164		40,649
Consumer Portfolio Segment [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	37,212		44,516
One-to-Four Family Residential [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	44,966		57,150
Commercial and Multifamily Residential [Member] | Covered Loans [Member]
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount	$ 181,634		$ 233,106