Comprehensive Income (Loss) (Components Of Comprehensive Income (Loss) In The Consolidated Statements Of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Comprehensive Income (Loss) [Line Items]
Reclassification, Before Tax	$ 1,978	$ 2,285	$ 7,150	$ 5,736
Reclassification, Tax Effect	(416)	(480)	(1,502)	(1,205)
Reclassification, Net of Tax	1,563	1,806	5,649	4,532
Total, Before Tax	(76,701)	66,000	(124,987)	166,114
Total, Tax Effect	16,079	(13,814)	26,182	(34,944)
Total, Net of Tax	(60,621)	52,187	(98,804)	131,171
URA(D) On Securities [Member]
Comprehensive Income (Loss) [Line Items]
Before Tax	(55,005)	48,819	(139,099)	132,405
Tax Effect	11,524	(10,247)	29,170	(27,807)
Net of Tax	(43,482)	38,572	(109,930)	104,598
Reclassification, Before Tax	2,683	(3,343)	12,751	36,591
Reclassification, Tax Effect	(524)	738	(2,660)	(7,767)
Reclassification, Net of Tax	2,160	(2,605)	10,092	28,824
Total, Net of Tax	(41,322)	35,967	(99,838)	133,422
Foreign Currency Translation Adjustments [Member]
Comprehensive Income (Loss) [Line Items]
Before Tax	(26,357)	18,239	(5,789)	(8,618)
Tax Effect	5,495	(3,825)	1,174	1,835
Net of Tax	(20,862)	14,414	(4,615)	(6,783)
Total, Net of Tax	(20,862)	14,414	(4,615)	(6,783)
Benefit Plan Net Gain (Loss) [Member]
Comprehensive Income (Loss) [Line Items]
Total, Net of Tax	$ 1,562	$ 1,806	$ 5,649	$ 4,532