Debt And Shareholders' Equity (Schedule Of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt And Shareholders' Equity [Line Items]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ 20,192	$ 6,957
Interest income expense, net, after tax	78,777	75,279
Income Tax Expense (Benefit)	41,448	51,176
Interest Income (Expense), Net	452,842	417,346
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	44,834	13,613
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1,875)	(481)
Beginning balance	(54,612)	(128,041)
Other comprehensive income (loss)	42,959	13,132
Ending balance	(11,653)	(114,909)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	6,920	1,088
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	665	0
Other Comprehensive Income (Loss), Tax	27,777	8,045
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Debt And Shareholders' Equity [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	32,168	11,424
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(17)	148
Beginning balance	(18,369)	(91,921)
Other comprehensive income (loss)	32,151	11,572
Ending balance	13,782	(80,349)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Debt And Shareholders' Equity [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	13,331	2,189
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(1,858)	(629)
Beginning balance	1,546	2,226
Other comprehensive income (loss)	11,473	1,560
Ending balance	13,019	3,786
Accumulated Defined Benefit Plans Adjustment [Member]
Debt And Shareholders' Equity [Line Items]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(665)	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Beginning balance	(37,789)	(38,346)
Other comprehensive income (loss)	(665)	0
Ending balance	(38,454)	(38,346)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Debt And Shareholders' Equity [Line Items]
Gain (Loss) on Investments, Excluding Other than Temporary Impairments	28	(239)
Interest Rate Contract [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Debt And Shareholders' Equity [Line Items]
Interest income expense, net, after tax	1,858	629
Income Tax Expense (Benefit)	1,139	387
Interest Income (Expense), Net	2,997	1,016
Fixed income securities gain loss [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Debt And Shareholders' Equity [Line Items]
Interest income expense, net, after tax	17	(148)
Income Tax Expense (Benefit)	$ 11	$ (91)