Accumulated Other Comprehensive Income (Summary Of Accumulated Other Comprehensive Income, Net Of Taxes) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	$ 10,646,751	$ 10,138,979	$ 10,641,577	$ 10,303,649
Net unrealized gains on available for sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	542,790	572,085
Net unrealized foreign exchange losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	(180,926)	(101,400)
Net unrealized losses on instrument specific credit risk
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	(18,916)	(34,432)
Net unrealized gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	446	(1,138)
Net minimum pension liability
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	(55,649)	(62,391)
AOCI Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Equity	$ 287,745	$ 372,724