Investment Securities (Schedule Of Fair Value And Unrealized Losses Of Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,908,718	$ 2,050,017
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	249,339	44,481
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,213,762	160,483
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	320,445	7,545
Debt Securities, Available-for-sale, Unrealized Loss Position	3,122,480	2,210,500
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	569,784	52,026
U.S. Treasury and agencies
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	714,139	197,529
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	81,728	2,749
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	116,674	28,378
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	22,928	1,446
Debt Securities, Available-for-sale, Unrealized Loss Position	830,813	225,907
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	104,656	4,195
Obligations of states and political subdivisions
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	224,486	75,200
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	24,966	1,153
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	31,605	2,162
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	9,795	135
Debt Securities, Available-for-sale, Unrealized Loss Position	256,091	77,362
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	34,761	1,288
Mortgage-backed securities and collateralized mortgage obligations
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	970,093	1,777,288
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	142,645	40,579
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,065,483	129,943
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	287,722	5,964
Debt Securities, Available-for-sale, Unrealized Loss Position	2,035,576	1,907,231
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 430,367	$ 46,543