Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				$ (891,412)	$ (1,086,864)
Other comprehensive income (loss) before reclassifications to current earnings				234,496	(139,560)
Amounts reclassified to current earnings from accumulated other comprehensive income				184,848	(2,666)
Current period other comprehensive income (loss), before tax				419,344	(142,226)
Income tax (expense) benefit				(104,836)	35,556
Current period other comprehensive income (loss), net of tax		$ 230,913	$ (157,239)	314,508	(106,670)
Ending balance		(576,904)	(1,193,534)	(576,904)	(1,193,534)
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]			240,695	(105,030)
Amounts reclassified to current earnings from accumulated other comprehensive income	[1]			192,938	8,444
Current period other comprehensive income (loss), before tax	[1]			433,633	(96,586)
Income tax (expense) benefit	[1]			(108,408)	24,146
Current period other comprehensive income (loss), net of tax	[1]			325,225	(72,440)
Ending balance	[1]	(589,776)	(1,197,355)	(589,776)	(1,197,355)
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				603	983
Current period other comprehensive income (loss), before tax				603	983
Income tax (expense) benefit				(150)	(245)
Current period other comprehensive income (loss), net of tax				453	738
Ending balance		(13,143)	(16,448)	(13,143)	(16,448)
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]			(6,199)	(34,530)
Amounts reclassified to current earnings from accumulated other comprehensive income	[2]			(8,693)	(12,093)
Current period other comprehensive income (loss), before tax	[2]			(14,892)	(46,623)
Income tax (expense) benefit	[2]			3,722	11,655
Current period other comprehensive income (loss), net of tax	[2]			(11,170)	(34,968)
Ending balance	[2]	$ 26,015	$ 20,269	$ 26,015	$ 20,269

[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.