Available-For-Sale And Held-To-Maturity Securities (Contractual Maturities) (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, debt maturities, within one year, Fair Value	[1]	$ 23,852
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	683,824
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	773,545
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,896,760
Available-for-sale Securities, debt maturities, Fair Value	[1]	3,377,981
Held-to-maturity Securities, debt maturities, within one year, Amortized Cost		40,061
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		59,573
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		431,327
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		2,658,806
Held-to-maturity Securities, Amortized cost	[2]	3,189,767	$ 3,038,405
U.S. Government Agency Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	1,175
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	3,244
Available-for-sale Securities, debt maturities, Fair Value	[1]	4,419
State And Municipal Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	201
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	375
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	16,815
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	55,026
Available-for-sale Securities, debt maturities, Fair Value	[1]	72,417
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	22,476
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	680,205
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	121,511
Available-for-sale Securities, debt maturities, Fair Value	[1]	824,192
Held-to-maturity Securities, debt maturities, within one year, Amortized Cost		40,061
Held-to-maturity Securities, Amortized cost	[2]	40,061	40,078
Asset-Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	579,868
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,481,542
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,061,410
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		270,998
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,309,165
Held-to-maturity Securities, Amortized cost	[2]	1,580,163	1,370,300
Mortgage Backed Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after five through ten years, fair value		55,351
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		360,192
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		160,329
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,349,641
Mortgage Backed Securities [Member] | Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	444
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	340,610
Available-for-sale Securities, debt maturities, Fair Value	[1]	341,054
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		160,329
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,349,641
Held-to-maturity Securities, Amortized cost	[2]	1,509,970	1,567,758
Mortgage Backed Securities [Member] | Commercial [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	54,907
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	17,851
Available-for-sale Securities, debt maturities, Fair Value	[1]	72,758
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		59,573
Held-to-maturity Securities, Amortized cost	[2]	59,573	59,581
Mortgage Backed Securities [Member] | Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,731
Available-for-sale Securities, debt maturities, Fair Value	[1]	$ 1,731
Held-to-maturity Securities, Amortized cost	[2]		$ 688

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

[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.