Accumulated Other Comprehensive Income (Schedule Of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance January 1		$ 77,080	$ 331,377
Other comprehensive loss before reclassifications to current earnings		(676,353)	(211,569)
Amounts reclassified to current earnings from accumulated other comprehensive income		(5,620)	(5,265)
Current period other comprehensive income (loss), before tax		(681,973)	(216,834)
Income tax (expense) benefit		170,493	54,209
Current period other comprehensive income (loss), net of tax		(511,480)	(162,625)
Balance March 31, 2022		(434,400)	168,752
Unrealized Gains (Losses) on Securities (1)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance January 1	[1]	23,174	263,801
Other comprehensive loss before reclassifications to current earnings	[1]	(676,353)	(211,569)
Amounts reclassified to current earnings from accumulated other comprehensive income	[1]	0	0
Current period other comprehensive income (loss), before tax	[1]	(676,353)	(211,569)
Income tax (expense) benefit	[1]	169,088	52,893
Current period other comprehensive income (loss), net of tax	[1]	(507,265)	(158,676)
Balance March 31, 2022	[1]	(484,091)	105,125
Pension Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance January 1		(20,668)	(25,118)
Other comprehensive loss before reclassifications to current earnings		0	0
Amounts reclassified to current earnings from accumulated other comprehensive income		430	583
Current period other comprehensive income (loss), before tax		430	583
Income tax (expense) benefit		(107)	(146)
Current period other comprehensive income (loss), net of tax		323	437
Balance March 31, 2022		(20,345)	(24,681)
Unrealized Gains (Losses) on Cash Flow Hedge Derivatives (2)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance January 1	[2]	74,574	92,694
Other comprehensive loss before reclassifications to current earnings	[2]	0	0
Amounts reclassified to current earnings from accumulated other comprehensive income	[2]	(6,050)	(5,848)
Current period other comprehensive income (loss), before tax	[2]	(6,050)	(5,848)
Income tax (expense) benefit	[2]	1,512	1,462
Current period other comprehensive income (loss), net of tax	[2]	(4,538)	(4,386)
Balance March 31, 2022	[2]	$ 70,036	$ 88,308

[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.