Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Securities available-for-sale, amortized cost	$ 1,510,142	$ 1,336,345
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	89,466,326	89,104,022
Common stock, shares outstanding (in shares)	81,255,683	80,893,379
Treasury stock shares (in shares)	8,210,643	8,210,643

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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