Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Consolidated Balance Sheets (Parentheticals) [Line Items]
Fixed income securities, held-to-maturity, fair value	$ 20,213	$ 21,975
Fixed income securities, available-for-sale, allowance for credit losses	7,180	0
Fixed income securities, available-for-sale, amortized cost	6,097,973	5,879,986
Commercial mortgage loan, fair value	30,595
Equity Securities, cost	158,045	72,061
Property and equipment, accumulated depreciation and amortization	$ 240,057	$ 227,566
Preferred stock, par value per share	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value per share	$ 2	$ 2
Common stock, shares authorized	360,000,000	360,000,000
Common stock, shares issued	103,961,596	103,484,159
Treasury stock, shares	44,126,894	44,023,006