Other Comprehensive Income (Change In Accumulated Other Comprehensive Income (Loss) By Component, Net Of Taxes And Noncontrolling Interest) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2018
Accumulated Other Comprehensive Income [Line Items]
Cumulative effect of adoption of ASU No. 2016-01, net of taxes			$ (2,613,242)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated other comprehensive income, beginning balance	$ (94,650)	$ 2,345,571
Other comprehensive income (loss) before reclassifications	325,522	(324,256)
Amounts reclassified from accumulated other comprehensive income (loss)	760	5,496
Total other comprehensive income (loss)	326,282	(318,760)
Accumulated other comprehensive income, ending balance	231,632	(184,892)
Accumulated other comprehensive income (loss), net of tax, adjusted			133,868
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			(2,615,734)
Cumulative effect of adoption of ASU No 2018-02			401,539
Accumulated other comprehensive income, beginning balance	48,060	2,477,973
Other comprehensive income (loss) before reclassifications	329,113	(306,069)
Amounts reclassified from accumulated other comprehensive income (loss)	760	5,496
Total other comprehensive income (loss)	329,873	(300,573)
Accumulated other comprehensive income, ending balance	377,933	(36,795)
Accumulated other comprehensive income (loss), net of tax, adjusted			263,778
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, beginning balance	(86,652)	(74,003)
Other comprehensive income (loss) before reclassifications	(5,929)	(19,928)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	(5,929)	(19,928)
Accumulated other comprehensive income, ending balance	(92,581)	(91,439)
Accumulated other comprehensive income (loss), net of tax, adjusted			(71,511)
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, beginning balance	(56,058)	(58,399)
Other comprehensive income (loss) before reclassifications	2,338	1,741
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	2,338	1,741
Accumulated other comprehensive income, ending balance	$ (53,720)	$ (56,658)
Accumulated other comprehensive income (loss), net of tax, adjusted			$ (58,399)