Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Investment securities:
Estimated fair value of held-to-maturity investment securities	$ 161,877	$ 146,508
Stockholders' Equity:
Preferred stock, par value	$ 0.00	$ 0.00
Nonvoting noncumulative preferred stock, authorized shares	100,000	100,000
Nonvoting noncumulative preferred stock, issued shares	5,000	5,000
Nonvoting noncumulative preferred stock, outstanding shares	5,000	5,000