Income Taxes (Reconciliation Of Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Computed tax expense (benefit) at 21%	$ 96,285	$ 79,394	$ (6,429)
Tax-exempt interest income	(12,270)	(12,909)	(13,507)
Dividends received deduction	(1,335)	(1,276)	(1,082)
State tax (benefit) expense	1,678	(869)	439
Nondeductible expenses	983	526	390
Change in federal tax contingency reserve	0	(2,588)	0
Reversal of AMT credit reduction (1)	0	0	(4,088)
Other, net	(1,447)	(4,296)	(610)
Income tax expense (benefit)	$ 83,894	$ 57,982	$ (24,887)
Reduction to alternative minimum tax credit, percent	6.60%