Available-for-Sale and Held-to-Maturity Securities (Schedule Of Amortized Cost And Fair Values Of Debt Securities By Contractual Maturity) (Details) - USD ($) $ in Thousands		Mar. 31, 2022		Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Available-for-sale Securities, debt maturities, within one year, Amortized Cost		$ 18,283		$ 36,671
Available-for-sale Securities, debt maturities, after one year through three years, Amortized Cost		266,201		217,606
Available-for-sale Securities, debt maturities, after three year through five years, Amortized Cost		155,351		192,271
Available-for-sale Securities, debt maturities, after five year through ten years, Amortized Cost		440,797		455,429
Available-for-sale Securities, debt maturities, after ten years, Amortized Cost		1,141,204		1,202,536
Available-for-sale Securities, Amortized cost		2,021,836		2,104,513
Available for sale securities, unrealized gains	[1]	5,354		26,406
Available-for-sale Securities, Gross unrealized losses	[1]	(101,046)		(17,026)
Available-for-sale Securities, debt maturities, within one year, Fair Value		18,356	[2]	36,899
Available-for-sale Securities, debt maturities, after one year through three years, Fair Value		266,561		222,942
Available-for-sale Securities, debt maturities, after three year through five years, Fair Value		146,970		196,380
Available-for-sale Securities, debt maturities, after five year through ten years, fair value		413,995	[2]	455,848
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		1,080,262	[2]	1,201,824
Available-for-sale Securities, debt maturities, Fair Value		1,926,144	[2]	2,113,893
Held-to-maturity Securities, debt maturities, after three through five years, Amortized Cost				2,825
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		2,217,675		2,282,162
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		3,098,621		3,063,571
Held-to-maturity Securities, Amortized cost	[3]	5,316,296		5,348,558
Held-to-maturity Securities, debt maturities, after three through five years, Fair Value				2,825
Held-to-maturity Securities, debt maturities, after five through ten years, Fair Value		2,198,375		2,278,597
Held-to-maturity Securities, debt maturities, after ten years, Fair Value		3,053,157		3,062,059
Held-to-maturity Securities, debt maturities, Fair Value	[3]	$ 5,251,532		$ 5,343,481

[1] Unrealized gains/(losses) related to available-for-sale securities are reported in accumulated other comprehensive income.

[2] Due to the immaterial amount of income recognized on tax-exempt securities, yields were not calculated on a tax-equivalent basis.

[3] Held-to-maturity securities are carried in the consolidated statements of financial condition at amortized cost, and the changes in the value of these securities, other than impairment charges, are not reported on the consolidated financial statements.