Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		$ (1,086,864)	$ 77,080
Other comprehensive income (loss) before reclassifications to current earnings		196,093	(676,353)
Amounts reclassified to current earnings from accumulated other comprehensive income		(937)	(5,620)
Current period other comprehensive income (loss), before tax		195,156	(681,973)
Income tax (expense) benefit		(48,790)	170,493
Current period other comprehensive income (loss), net of tax		146,366	(511,480)
Ending balance		(940,498)	(434,400)
Unrealized Gains (Losses) on Securities (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[1]	(1,124,915)	23,174
Other comprehensive income (loss) before reclassifications to current earnings	[1]	186,868	(676,353)
Amounts reclassified to current earnings from accumulated other comprehensive income	[1]	3,088	0
Current period other comprehensive income (loss), before tax	[1]	189,956	(676,353)
Income tax (expense) benefit	[1]	(47,490)	169,088
Current period other comprehensive income (loss), net of tax	[1]	142,466	(507,265)
Ending balance	[1]	(982,449)	(484,091)
Pension Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance		(17,186)	(20,668)
Other comprehensive income (loss) before reclassifications to current earnings		0	0
Amounts reclassified to current earnings from accumulated other comprehensive income		360	430
Current period other comprehensive income (loss), before tax		360	430
Income tax (expense) benefit		(90)	(107)
Current period other comprehensive income (loss), net of tax		270	323
Ending balance		(16,916)	(20,345)
Unrealized Gains (Losses) on Cash Flow Hedge Derivatives (2)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	[2]	55,237	74,574
Other comprehensive income (loss) before reclassifications to current earnings	[2]	9,225	0
Amounts reclassified to current earnings from accumulated other comprehensive income	[2]	(4,385)	(6,050)
Current period other comprehensive income (loss), before tax	[2]	4,840	(6,050)
Income tax (expense) benefit	[2]	(1,210)	1,512
Current period other comprehensive income (loss), net of tax	[2]	3,630	(4,538)
Ending balance	[2]	$ 58,867	$ 70,036

[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.