CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Held to Maturity, fair value	$ 159,781	$ 921,800
Common stock, par value (in dollars per share)	$ 1.25	$ 1.25
Common stock, shares authorized (in shares)	80,000,000	40,000,000
Common stock, shares issued (in shares)	37,845,224	37,802,352
Treasury stock, (in shares)	4,120,475	2,802,019