Available-For-Sale And Held-To-Maturity Securities (Schedule Of Amortized Cost And Fair Values Of The Available For Sale Securities And Held To Maturity Securities) (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		$ 3,380,629	$ 3,190,090
Available for sale securities, unrealized gains	[1]	14,709	11,634
Available-for-sale Securities, Gross unrealized losses	[1]	(17,357)	(20,411)
Available-for-sale securities		3,377,981	3,181,313
Held-to-maturity Securities, Amortized cost	[2]	3,189,767	3,038,405
Held-to-maturity Securities, Gross unrealized gains	[2]	28,626	22,595
Held-to-maturity Securities, Gross unrealized losses	[2]	(19,280)	(20,446)
Held-to-maturity securities, Estimated fair value	[2]	3,199,113	3,040,554
U.S. Government Agency Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		4,437	4,213
Available for sale securities, unrealized gains	[1]	1	2
Available-for-sale Securities, Gross unrealized losses	[1]	(19)	(18)
Available-for-sale securities		4,419	4,197
State And Municipal Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		75,827	76,066
Available-for-sale Securities, Gross unrealized losses	[1]	(3,410)	(3,576)
Available-for-sale securities		72,417	72,490
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		828,951	830,695
Available for sale securities, unrealized gains	[1]	2,067	1,418
Available-for-sale Securities, Gross unrealized losses	[1]	(6,826)	(8,602)
Available-for-sale securities		824,192	823,511
Held-to-maturity Securities, Amortized cost	[2]	40,061	40,078
Held-to-maturity Securities, Gross unrealized gains	[2]	75	30
Held-to-maturity securities, Estimated fair value	[2]	40,136	40,108
Asset-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		2,049,733	1,858,929
Available for sale securities, unrealized gains	[1]	12,333	9,857
Available-for-sale Securities, Gross unrealized losses	[1]	(656)	(1,068)
Available-for-sale securities		2,061,410	1,867,718
Held-to-maturity Securities, Amortized cost	[2]	1,580,163	1,370,300
Held-to-maturity Securities, Gross unrealized gains	[2]	11,238	6,242
Held-to-maturity Securities, Gross unrealized losses	[2]	(2,378)	(3,396)
Held-to-maturity securities, Estimated fair value	[2]	1,589,023	1,373,146
Mortgage Backed Securities [Member] | Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		342,751	340,738
Available for sale securities, unrealized gains	[1]	261	298
Available-for-sale Securities, Gross unrealized losses	[1]	(1,958)	(2,304)
Available-for-sale securities		341,054	338,732
Held-to-maturity Securities, Amortized cost	[2]	1,509,970	1,567,758
Held-to-maturity Securities, Gross unrealized gains	[2]	15,734	14,537
Held-to-maturity Securities, Gross unrealized losses	[2]	(16,902)	(17,037)
Held-to-maturity securities, Estimated fair value	[2]	1,508,802	1,565,258
Mortgage Backed Securities [Member] | Commercial [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		77,077	77,417
Available for sale securities, unrealized gains	[1]	47	59
Available-for-sale Securities, Gross unrealized losses	[1]	(4,366)	(4,703)
Available-for-sale securities		72,758	72,773
Held-to-maturity Securities, Amortized cost	[2]	59,573	59,581
Held-to-maturity Securities, Gross unrealized gains	[2]	1,579	1,786
Held-to-maturity securities, Estimated fair value	[2]	61,152	61,367
Mortgage Backed Securities [Member] | Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, Amortized cost		1,853	2,032
Available-for-sale Securities, Gross unrealized losses	[1]	(122)	(140)
Available-for-sale securities		$ 1,731	1,892
Held-to-maturity Securities, Amortized cost	[2]		688
Held-to-maturity Securities, Gross unrealized losses	[2]		(13)
Held-to-maturity securities, Estimated fair value	[2]		$ 675

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

[2] 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.