Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Investment securities [Abstract]
Investment Securities, fair value	$ 347,015	$ 367,298
Allowance for real estate and other repossessed assets	$ 12,499	$ 13,665
Shareholders' equity: [Abstract]
Common stock, par value (in dollars per share)	$ 0.00006	$ 0.00006
Common stock, shares authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, shares issued (in shares)	75,756,056	75,711,492
Common stock, shares outstanding (in shares)	75,756,056	75,711,492
Treasury stock, shares at cost (in shares)	4,562,286	3,588,560

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