Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Securities available-for-sale, amortized cost	$ 984,075	$ 969,359
Less: Unearned income on loans	(6,985)	(7,767)
Other real estate owned covered by FDIC loss share	25,727	26,987
Common stock, par value
Common stock, shares authorized	63,033	63,033
Common stock, shares outstanding	39,844	39,686
Covered Loans [Member]
Allowance for losses on covered loans	(29,489)	(30,056)
Other real estate owned covered by FDIC loss share	$ 13,811	$ 16,311