Consolidated Balance Sheets - Unaudited (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Investment securities available for sale, at fair value, amortized cost	$ 562,528	$ 745,328
Investment securities held to maturity at amortized cost, fair value	$ 10,324	$ 8,438
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	24,577,248	24,545,348
Common stock, outstanding (in shares)	20,167,729	20,163,816
Treasury stock (in shares)	4,409,519	4,381,532

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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