CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized cost of securities	$ 6,024,225	$ 3,311,433
Held to maturity securities, fair value	$ 100,041	$ 100,484
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	60,000,000
Common stock, shares issued (in shares)	42,093,862	36,704,278
Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	6,104	6,104
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock	$ 0	$ 0
Series A Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	16,000	16,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock	$ 0	$ 0
Series C Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	81,698	81,698
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock	$ 0	$ 0
Series D Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	3,000	3,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock	$ 0	$ 0
Series E Preferred Stock
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	11,500	0
Preferred stock, shares issued (in shares)	11,500	0
Preferred stock, shares outstanding (in shares)	11,500	0
Preferred stock	$ 110,705	$ 0