Other Comprehensive Income (Change In Accumulated Other Comprehensive Income By Component, Net Of Taxes And Noncontrolling Interest) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	$ 1,565,866	$ 1,354,508
Other comprehensive income before reclassifications	353,840	390,462
Amounts reclassified from accumulated other comprehensive income	(7,773)	(22,693)
Total other comprehensive income	346,067	367,769
Accumulated other comprehensive income, ending balance	1,911,933	1,722,277
Unrealized Holding Gains On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	1,714,930	1,472,762
Other comprehensive income before reclassifications	350,349	388,273
Amounts reclassified from accumulated other comprehensive income	(9,391)	(23,550)
Total other comprehensive income	340,958	364,723
Accumulated other comprehensive income, ending balance	2,055,888	1,837,485
Foreign Currency [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	(84,406)	(72,696)
Other comprehensive income before reclassifications	3,491	2,189
Amounts reclassified from accumulated other comprehensive income	0	0
Total other comprehensive income	3,491	2,189
Accumulated other comprehensive income, ending balance	(80,915)	(70,507)
Net Actuarial Pension Loss [Member]
Accumulated Other Comprehensive Income [Line Items]
Accumulated other comprehensive income, beginning balance	(64,658)	(45,558)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	1,618	857
Total other comprehensive income	1,618	857
Accumulated other comprehensive income, ending balance	$ (63,040)	$ (44,701)