Other Comprehensive Income (Loss) (Change In Accumulated Other Comprehensive Income (Loss) By Component, Net Of Taxes And Noncontrolling Interest) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2018
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			$ (2,623,773)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated Other Comprehensive Income (Loss), Net of Tax, Adjusted			123,337
Accumulated other comprehensive income, beginning balance	$ (94,650)	$ 2,345,571
Other comprehensive income (loss) before reclassifications	156,064	(111,347)
Amounts reclassified from accumulated other comprehensive income (loss)	(246)	814
Total other comprehensive income (loss)	155,818	(110,533)
Accumulated other comprehensive income, ending balance	61,168	12,804
Unrealized Holding Gains On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			(2,626,265)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated Other Comprehensive Income (Loss), Net of Tax, Adjusted			253,247
Accumulated other comprehensive income, beginning balance	48,060	2,477,973
Other comprehensive income (loss) before reclassifications	152,331	(116,922)
Amounts reclassified from accumulated other comprehensive income (loss)	(246)	814
Total other comprehensive income (loss)	152,085	(116,108)
Accumulated other comprehensive income, ending balance	200,145	137,139
Foreign Currency [Member]
Accumulated Other Comprehensive Income [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			0
Accumulated Other Comprehensive Income (Loss), Net of Tax, Adjusted			(71,511)
Accumulated other comprehensive income, beginning balance	(86,652)	(74,003)
Other comprehensive income (loss) before reclassifications	2,372	4,911
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	2,372	4,911
Accumulated other comprehensive income, ending balance	(84,280)	(66,600)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income [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, beginning balance	(56,058)	(58,399)
Other comprehensive income (loss) before reclassifications	1,361	664
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	1,361	664
Accumulated other comprehensive income, ending balance	$ (54,697)	$ (57,735)