Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Investment securities [Abstract]
Investment Securities, Fair Value	$ 599,062	$ 629,159	$ 642,042
Real estate and other repossessed assets, Valuation allowance	$ 9,448	$ 12,622	$ 17,296
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 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)	74,817,155	74,530,364	74,428,730
Common stock, shares outstanding (in shares)	74,817,155	74,530,364	74,428,730
Treasury stock, shares at cost (in shares)	8,950,838	8,636,332	5,483,591