Pension Plans And Postretirement Benefits (Schedule Of Plan's Assets At Fair Value) (Details) - U.S. Pension Plans [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 117,719	$ 240,010	$ 239,080
Jefferies [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	47,031	51,085
Jefferies [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	33,618	37,629
Jefferies [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	13,413	13,456
Jefferies [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	487	373
Jefferies [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	487	373
Jefferies [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Listed Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	29,156	31,327
Jefferies [Member] | Listed Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	29,156	31,327
Jefferies [Member] | Listed Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	6,598	6,482
Jefferies [Member] | Corporate Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	6,598	6,482
Jefferies [Member] | Foreign Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	2,140	1,321
Jefferies [Member] | Foreign Corporate Debt Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Foreign Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	2,140	1,321
Jefferies [Member] | U.S. Government Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,975	5,929
Jefferies [Member] | U.S. Government Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,975	5,929
Jefferies [Member] | U.S. Government Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Agency Mortgage-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,504	3,883
Jefferies [Member] | Agency Mortgage-Backed Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Agency Mortgage-Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,504	3,883
Jefferies [Member] | Commercial Mortgage Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	425	1,080
Jefferies [Member] | Commercial Mortgage Backed Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Commercial Mortgage Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	425	1,080
Jefferies [Member] | Asset-Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	746	690
Jefferies [Member] | Asset-Backed Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Jefferies [Member] | Asset-Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	746	690
WilTel [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	70,688	188,925
WilTel [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	9,014	18,388
WilTel [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	61,674	170,537
WilTel [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,026	14,669
WilTel [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3,026	14,669
WilTel [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
WilTel [Member] | U.S. Government And Federal Agency Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5,988	3,719
WilTel [Member] | U.S. Government And Federal Agency Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5,988	3,719
WilTel [Member] | U.S. Government And Federal Agency Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
WilTel [Member] | Public Utilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	8,978	15,669
WilTel [Member] | Public Utilities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
WilTel [Member] | Public Utilities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	8,978	15,669
WilTel [Member] | All Other Corporate Bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	52,696	154,868
WilTel [Member] | All Other Corporate Bonds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
WilTel [Member] | All Other Corporate Bonds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 52,696	$ 154,868