Available-For-Sale And Held-To-Maturity Securities (Contractual Maturities) (Details) - USD ($) $ in Thousands		Jun. 30, 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]	$ 142,514
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	571,338
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	759,825
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,981,696
Available-for-sale Securities, debt maturities, Fair Value	[1]	3,455,373
Held-to-maturity Securities, debt maturities, within one year, Amortized Cost		40,045
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		59,518
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		497,440
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		2,710,967
Held-to-maturity Securities, Amortized cost	[2]	3,307,970	$ 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]	824
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	3,741
Available-for-sale Securities, debt maturities, Fair Value	[1]	4,565
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]	200
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]	16,738
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	55,069
Available-for-sale Securities, debt maturities, Fair Value	[1]	72,382
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]	141,490
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	567,222
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	262,419
Available-for-sale Securities, debt maturities, Fair Value	[1]	971,131
Held-to-maturity Securities, debt maturities, within one year, Amortized Cost		40,045
Held-to-maturity Securities, Amortized cost	[2]	40,045	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]	424,822
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,589,106
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,013,928
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		335,011
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,419,082
Held-to-maturity Securities, Amortized cost	[2]	1,754,093	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		55,846
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		337,521
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		162,429
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,291,885
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]	412
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	318,650
Available-for-sale Securities, debt maturities, Fair Value	[1]	319,062
Held-to-maturity Securities, debt maturities, after five year through ten, Amortized Cost		162,429
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,291,885
Held-to-maturity Securities, Amortized cost	[2]	1,454,314	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]	55,434
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	17,254
Available-for-sale Securities, debt maturities, Fair Value	[1]	72,688
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		59,518
Held-to-maturity Securities, Amortized cost	[2]	59,518	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]	1,617
Available-for-sale Securities, debt maturities, Fair Value	[1]	$ 1,617
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.