Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (891,412)	$ (1,086,864)
Other comprehensive income (loss) before reclassifications to current earnings		(58,536)	196,093
Amounts reclassified to current earnings from accumulated other comprehensive income		5,715	(937)
Current period other comprehensive income (loss), before tax		(52,821)	195,156
Income tax (expense) benefit		13,206	(48,790)
Current period other comprehensive income (loss), net of tax		(39,615)	146,366
Ending balance		(931,027)	(940,498)
Unrealized Gains (Losses) on Securities (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(915,001)	(1,124,915)
Other comprehensive income (loss) before reclassifications to current earnings	[1]	(35,671)	186,868
Amounts reclassified to current earnings from accumulated other comprehensive income	[1]	8,469	3,088
Current period other comprehensive income (loss), before tax	[1]	(27,202)	189,956
Income tax (expense) benefit	[1]	6,801	(47,490)
Current period other comprehensive income (loss), net of tax	[1]	(20,401)	142,466
Ending balance	[1]	(935,402)	(982,449)
Pension Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(13,596)	(17,186)
Other comprehensive income (loss) before reclassifications to current earnings		0	0
Amounts reclassified to current earnings from accumulated other comprehensive income		235	360
Current period other comprehensive income (loss), before tax		235	360
Income tax (expense) benefit		(59)	(90)
Current period other comprehensive income (loss), net of tax		176	270
Ending balance		(13,420)	(16,916)
Unrealized Gains (Losses) on Cash Flow Hedge Derivatives (2)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[2]	37,185	55,237
Other comprehensive income (loss) before reclassifications to current earnings	[2]	(22,865)	9,225
Amounts reclassified to current earnings from accumulated other comprehensive income	[2]	(2,989)	(4,385)
Current period other comprehensive income (loss), before tax	[2]	(25,854)	4,840
Income tax (expense) benefit	[2]	6,464	(1,210)
Current period other comprehensive income (loss), net of tax	[2]	(19,390)	3,630
Ending balance	[2]	$ 17,795	$ 58,867

[1] The pre-tax amounts reclassified from accumulated other comprehensive income to current earnings are included in "investment securities gains (losses), net" in the consolidated statements of income.

[2] The pre-tax amounts reclassified from accumulated other comprehensive income to current earnings are included in "interest and fees on loans" in the consolidated statements of income.