Other Comprehensive Income (Loss) (Change In Accumulated Other Comprehensive Income By Component, Net Of Taxes And Noncontrolling Interests) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes				$ (2,595,484)
Cumulative effect of adoption of ASU No 2018-02				402,853
Accumulated other comprehensive income (loss), net of tax, adjusted				152,940
Accumulated other comprehensive income (loss), beginning balance	$ (94,650)	$ 2,345,571	$ 1,565,866
Other comprehensive income (loss) before reclassifications	302,436	(257,780)	800,834
Amounts reclassified from accumulated other comprehensive income (loss)	986	10,190	(21,129)
Total other comprehensive income (loss)	303,422	(247,590)	779,705
Accumulated other comprehensive income (loss), ending balance	208,772	(94,650)	2,345,571
Unrealized Holding Gains On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes				(2,597,976)
Cumulative effect of adoption of ASU No 2018-02				401,539
Accumulated other comprehensive income (loss), net of tax, adjusted				281,536
Accumulated other comprehensive income (loss), beginning balance	48,060	2,477,973	1,714,930
Other comprehensive income (loss) before reclassifications	299,125	(241,325)	787,339
Amounts reclassified from accumulated other comprehensive income (loss)	(1,148)	7,849	(24,296)
Total other comprehensive income (loss)	297,977	(233,476)	763,043
Accumulated other comprehensive income (loss), ending balance	346,037	48,060	2,477,973
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes				2,492
Cumulative effect of adoption of ASU No 2018-02				1,314
Accumulated other comprehensive income (loss), net of tax, adjusted				(70,197)
Accumulated other comprehensive income (loss), beginning balance	(86,652)	(74,003)	(84,406)
Other comprehensive income (loss) before reclassifications	403	(16,455)	10,403
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Total other comprehensive income (loss)	403	(16,455)	10,403
Accumulated other comprehensive income (loss), ending balance	(86,249)	(86,652)	(74,003)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes				0
Cumulative effect of adoption of ASU No 2018-02				0
Accumulated other comprehensive income (loss), net of tax, adjusted				$ (58,399)
Accumulated other comprehensive income (loss), beginning balance	(56,058)	(58,399)	(64,658)
Other comprehensive income (loss) before reclassifications	2,908	0	3,092
Amounts reclassified from accumulated other comprehensive income (loss)	2,134	2,341	3,167
Total other comprehensive income (loss)	5,042	2,341	6,259
Accumulated other comprehensive income (loss), ending balance	$ (51,016)	$ (56,058)	$ (58,399)