Available-For-Sale And Held-To-Maturity Securities (Contractual Maturities) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, within one year, Fair Value	[1]	$ 953
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	507,094
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	297,432
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	1,319,987
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,125,466
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		40,128
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		261,778
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,726,273
Held-to-maturity Securities, Amortized cost	[2]	2,028,179	$ 1,855,399
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]	953
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	827
Available-for-sale Securities, debt maturities, Fair Value	[1]	1,780
State And Municipal 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]	11,017
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	63,088
Available-for-sale Securities, debt maturities, Fair Value	[1]	74,105
Corporate Fixed Income Securities [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	506,215
Available-for-sale Securities, debt maturities, after five through ten years, fair value	[1]	34,994
Available-for-sale Securities, debt maturities, Fair Value	[1]	541,209
Held-to-maturity Securities, debt maturities, after one year through five, Amortized Cost		40,128
Held-to-maturity Securities, Amortized cost	[2]	40,128	40,145
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]	250,844
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	835,049
Available-for-sale Securities, debt maturities, Fair Value	[1]	1,085,893
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		497,134
Held-to-maturity Securities, Amortized cost	[2]	497,134	496,996
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		577
Availably-for-sale Securities, debt maturities, after ten years, Fair Value		421,850
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		261,778
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,229,139
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]	577
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	400,054
Available-for-sale Securities, debt maturities, Fair Value	[1]	400,631
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		202,242
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		1,228,344
Held-to-maturity Securities, Amortized cost	[2]	1,430,586	1,257,808
Mortgage Backed Securities [Member] | Commercial [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]	19,565
Available-for-sale Securities, debt maturities, Fair Value	[1]	19,565
Held-to-maturity Securities, debt maturities, after five through ten years, Amortized Cost		59,536
Held-to-maturity Securities, Amortized cost	[2]	59,536	59,521
Mortgage Backed Securities [Member] | Non-Agency [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available-for-sale Securities, debt maturities, after one year through five, Fair Value	[1]	52
Availably-for-sale Securities, debt maturities, after ten years, Fair Value	[1]	2,231
Available-for-sale Securities, debt maturities, Fair Value	[1]	2,283
Held-to-maturity Securities, debt maturities, after ten years, Amortized Cost		795
Held-to-maturity Securities, Amortized cost	[2]	$ 795	$ 929

[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.