Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Investment securities [Abstract]
Investment Securities, fair value	$ 580,310	$ 629,159	$ 643,091
Allowance for real estate and other repossessed assets	$ 9,524	$ 12,622	$ 12,874
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)	74,866,429	74,530,364	74,461,234
Common stock, shares outstanding (in shares)	74,866,429	74,530,364	74,461,234
Treasury stock, shares at cost (in shares)	8,955,975	8,636,332	6,748,203