Investment Securities (Schedule Of Fair Value And Unrealized Losses Of Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 2,633,216	$ 2,050,017
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	253,455	44,481
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	669,721	160,483
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	130,850	7,545
Debt Securities, Available-for-sale, Unrealized Loss Position	3,302,937	2,210,500
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	384,305	52,026
U.S. Treasury and agencies
Investment Holdings [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	848,104	197,529
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	58,599	2,749
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	24,771	28,378
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5,063	1,446
Debt Securities, Available-for-sale, Unrealized Loss Position	872,875	225,907
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	63,662	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	200,165	75,200
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	21,898	1,153
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,073	2,162
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	926	135
Debt Securities, Available-for-sale, Unrealized Loss Position	204,238	77,362
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	22,824	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	1,584,947	1,777,288
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	172,958	40,579
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	640,877	129,943
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	124,861	5,964
Debt Securities, Available-for-sale, Unrealized Loss Position	2,225,824	1,907,231
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 297,819	$ 46,543