Variable Interest Entities (Assets And Liabilities Of Consolidated VIEs) (Details) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Cash		$ 4,661,937	$ 3,807,558	$ 3,030,936	$ 3,638,648
Financial instruments owned		15,585,116	15,286,286
Securities purchased under agreement to resell		4,345,461	3,862,488
Receivables		5,874,580	4,425,178
Loans to and investments in associated companies		2,239,423	2,125,098
Other		1,807,490	1,635,664
Total assets	[1]	48,376,102	45,071,307
Other secured financings		763,043	1,026,429
Long-term debt		8,084,886	7,380,443
Total liabilities	[1]	37,262,994	34,305,849
Noncontrolling interests		188,858	175,549
Securitization Vehicles [Member]
Variable Interest Entity [Line Items]
Cash		8,400	18,400
Financial instruments owned		36,300	86,600
Securities purchased under agreement to resell		370,300	733,500
Receivables		391,600	277,700
Loans to and investments in associated companies		0	0
Other		21,300	14,500
Total assets		827,900	1,130,700
Other secured financings		781,100	1,083,800
Long-term debt		0	24,100
Other		48,500	22,300
Total liabilities		829,600	1,130,200
Noncontrolling interests		0	0
Real Estate Investment Vehicles [Member]
Variable Interest Entity [Line Items]
Cash		1,300	2,200
Financial instruments owned		0	0
Securities purchased under agreement to resell		0	0
Receivables		270,000	296,900
Loans to and investments in associated companies		118,900	108,700
Other		6,800	10,800
Total assets		397,000	418,600
Other secured financings		0	0
Long-term debt		213,400	243,900
Other		9,300	11,700
Total liabilities		222,700	255,600
Noncontrolling interests		104,900	98,700
Jefferies [Member]
Variable Interest Entity [Line Items]
Secured financings eliminated in consolidation		38,900	57,600
Consolidation, Eliminations [Member]
Variable Interest Entity [Line Items]
Intercompany payables		$ 40,800	$ 20,000

[1] Total assets include assets related to variable interest entities of $854.5 million and $815.8 million at June 30, 2017 and December 31, 2016, respectively, and Total liabilities include liabilities related to variable interest entities of $966.0 million and $1,284.7 million at June 30, 2017 and December 31, 2016, respectively. See Note 8 for additional information related to variable interest entities.