CONSOLIDATED BALANCE SHEETS (Unaudited) Parentheticals - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Investment securities available-for-sale at amortized cost	$ 961,351	$ 966,900
Investment securities held-to-maturity at fair value	$ 46,096	$ 47,949
Common stock, par value (in dollars per share)	$ 1.00
Common stock, shares authorized (in shares)	170,000,000
Common stock, shares issued (in shares)	81,800,486	83,265,674
Common stock, shares, outstanding (in shares)	81,800,486	83,265,674