CONSOLIDATED BALANCE SHEETS (Unaudited) Parentheticals - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Investment securities available-for-sale at amortized cost	$ 960,550	$ 1,018,774
Investment securities held-to-maturity at fair value	$ 53,929	$ 68,595
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	170,000,000	170,000,000
Common stock, shares issued (in shares)	83,774,335	83,655,651
Common stock, shares, outstanding (in shares)	83,774,335	83,655,651