Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss), Net Of Tax, In The Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 10,139,180
Current period change	(844,343)	$ (299,820)
Balance	9,527,629	9,682,882
URA(D) On Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	239,397	724,159
Current period change	(810,999)	(292,281)
Balance	(571,602)	431,878
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(177,481)	(115,390)
Current period change	(34,102)	(9,582)
Balance	(211,583)	(124,972)
Benefit Plan Net Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(50,392)	(73,870)
Current period change	758	2,043
Balance	(49,634)	(71,827)
Accumulated Other Comprehensive Income (Loss), Net of Deferred Income Taxes [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	11,523	534,899
Current period change	(844,343)	(299,820)
Balance	$ (832,820)	$ 235,079