Covered Assets and FDIC Loss-sharing Asset (Analysis and Allowance for Losses on Covered Loans) (Details) (USD $) In Thousands, unless otherwise specified							3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Covered Loans [Member]	Dec. 31, 2011 Covered Loans [Member]	Mar. 31, 2011 Covered Loans [Member]	Dec. 31, 2010 Covered Loans [Member]	Mar. 31, 2012 Commercial Portfolio Segment [Member] Covered Loans [Member] risk_rating	Dec. 31, 2011 Commercial Portfolio Segment [Member] Covered Loans [Member] risk_rating	Mar. 31, 2012 Real Estate Portfolio Segment [Member] Covered Loans [Member]	Dec. 31, 2011 Real Estate Portfolio Segment [Member] Covered Loans [Member]	Mar. 31, 2012 Real Estate Portfolio Segment [Member] Covered Loans [Member] One-to-Four Family Residential [Member] risk_rating	Dec. 31, 2011 Real Estate Portfolio Segment [Member] Covered Loans [Member] One-to-Four Family Residential [Member] risk_rating	Mar. 31, 2012 Real Estate Portfolio Segment [Member] Covered Loans [Member] Commercial and Multifamily Residential [Member] risk_rating	Dec. 31, 2011 Real Estate Portfolio Segment [Member] Covered Loans [Member] Commercial and Multifamily Residential [Member] risk_rating	Mar. 31, 2012 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member]	Dec. 31, 2011 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member]	Mar. 31, 2012 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member] One-to-Four Family Residential [Member] risk_rating	Dec. 31, 2011 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member] One-to-Four Family Residential [Member] risk_rating	Mar. 31, 2012 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member] Commercial and Multifamily Residential [Member] risk_rating	Dec. 31, 2011 Real Estate Construction Portfolio Segment [Member] Covered Loans [Member] Commercial and Multifamily Residential [Member] risk_rating	Mar. 31, 2012 Consumer Portfolio Segment [Member] Covered Loans [Member] risk_rating	Dec. 31, 2011 Consumer Portfolio Segment [Member] Covered Loans [Member] risk_rating
Covered Assets And FDIC Loss Sharing Asset [Line Items]
Loans and Leases Receivable, Gross, Carrying Amount			$ 666,884	$ 721,313			$ 175,623	$ 195,737	$ 373,935	$ 390,636	$ 74,733	$ 79,328	$ 299,202	$ 311,308	$ 65,665	$ 78,063	$ 44,335	$ 54,402	$ 21,330	$ 23,661	$ 51,661	$ 56,877
Weighted Average Risk Rating							6.00	6.05			5.35	5.32	5.57	5.65			7.25	7.32	7.04	7.32	4.71	4.84
Valuation discount resulting from acquisition accounting			144,767	184,440
Allowance for loan losses			20,504	4,944	5,633	6,055	6,320	977	9,787	3,361	2,947	678	6,840	2,683	2,315	222	1,604	136	711	86	2,082	384
Loans, net	$ 2,821,148	$ 2,827,259	$ 501,613	$ 531,929