Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Securities:
Investments securities, fair value	$ 369,247	$ 346,105	$ 363,886
Interest bearing deposits:
Interest bearing deposit liabilities measured at fair value	$ 0	$ 27,414	$ 27,957
Shareholders' equity:
Common stock, par value	$ 0.00006	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	71,100,444	70,815,563	70,616,414
Common stock, shares outstanding (in shares)	71,100,444	70,815,563	70,616,414
Treasury stock, shares (in shares)	2,637,575	2,607,874	2,535,617