Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Securities available for sale, amortized cost	$ 2,384,221	$ 2,426,924
Securities held to maturity	1,223	1,447
Loans held for sale at fair value	$ 495,932	$ 384,375
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	105,684,479	105,494,290
Common stock, shares in treasury	3,960,879	3,940,619