Loans To And Investments In Associated Companies (Schedule of Loans to and Investments in Associated Companies) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	$ 1,712,568	$ 1,258,341	$ 807,474
Amounts at date of Jefferies acquisition			766,894
Income related to associated companies	110,281	138,527	119,041
Income (losses) related to associated companies classified as Other revenue	75,717	90,242	92,180
Contributions to (distributions from) associated companies, net	(120,860)	26,878	(129,703)
Other, including foreign exchange and unrealized gain (losses)	(20,337)	198,580	(397,545)
Loans to and investments in associated companies ending balance	1,757,369	1,712,568	1,258,341
Noncontrolling interests	64,679	67,864
Jefferies Finance [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	508,891	470,537	0
Amounts at date of Jefferies acquisition			510,684
Income related to associated companies	0	0	0
Income (losses) related to associated companies classified as Other revenue	40,884	72,701	57,795
Contributions to (distributions from) associated companies, net	(21,200)	(34,347)	(97,942)
Other, including foreign exchange and unrealized gain (losses)	0	0	0
Loans to and investments in associated companies ending balance	528,575	508,891	470,537
Jefferies LoanCore [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	258,947	224,037	0
Amounts at date of Jefferies acquisition			217,299
Income related to associated companies	0	0	0
Income (losses) related to associated companies classified as Other revenue	36,554	18,793	35,300
Contributions to (distributions from) associated companies, net	(6,760)	16,117	(28,562)
Other, including foreign exchange and unrealized gain (losses)	0	0	0
Loans to and investments in associated companies ending balance	288,741	258,947	224,037
Berkadia [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	208,511	182,573	172,942
Amounts at date of Jefferies acquisition			0
Income related to associated companies	78,092	101,187	84,678
Income (losses) related to associated companies classified as Other revenue	0	0	0
Contributions to (distributions from) associated companies, net	(89,560)	(72,721)	(69,016)
Other, including foreign exchange and unrealized gain (losses)	(6,057)	(2,528)	(6,031)
Loans to and investments in associated companies ending balance	190,986	208,511	182,573
Garcadia [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	167,939	120,017	82,425
Amounts at date of Jefferies acquisition			0
Income related to associated companies	53,182	49,416	39,399
Income (losses) related to associated companies classified as Other revenue	0	0	0
Contributions to (distributions from) associated companies, net	(48,461)	(1,494)	(1,807)
Other, including foreign exchange and unrealized gain (losses)	0	0	0
Loans to and investments in associated companies ending balance	172,660	167,939	120,017
Linkem [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	159,054	173,577	86,424
Amounts at date of Jefferies acquisition			0
Income related to associated companies	(15,577)	(14,633)	(22,719)
Income (losses) related to associated companies classified as Other revenue	0	0	0
Contributions to (distributions from) associated companies, net	21,138	18,390	107,385
Other, including foreign exchange and unrealized gain (losses)	(14,466)	(18,280)	2,487
Loans to and investments in associated companies ending balance	150,149	159,054	173,577
HomeFed Corporation [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	271,782	52,923	49,384
Amounts at date of Jefferies acquisition			0
Income related to associated companies	3,596	3,150	3,539
Income (losses) related to associated companies classified as Other revenue	0	0	0
Contributions to (distributions from) associated companies, net	0	0	0
Other, including foreign exchange and unrealized gain (losses)	0	215,709	0
Loans to and investments in associated companies ending balance	275,378	271,782	52,923
Golden Queen Mining Company, LLC [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	103,598	0	0
Amounts at date of Jefferies acquisition			0
Income related to associated companies	(1,775)	(1,402)	0
Income (losses) related to associated companies classified as Other revenue	0	0	0
Contributions to (distributions from) associated companies, net	12,500	105,000	0
Other, including foreign exchange and unrealized gain (losses)	0	0	0
Loans to and investments in associated companies ending balance	114,323	103,598	0
Noncontrolling interests	33,700	33,700
Other [Member]
Equity Method Investment [Roll Forward]
Loans to and investments in associated companies beginning balance	33,846	34,677	416,299
Amounts at date of Jefferies acquisition			38,911
Income related to associated companies	(7,237)	809	14,144
Income (losses) related to associated companies classified as Other revenue	(1,721)	(1,252)	(915)
Contributions to (distributions from) associated companies, net	11,483	(4,067)	(39,761)
Other, including foreign exchange and unrealized gain (losses)	186	3,679	(394,001)
Loans to and investments in associated companies ending balance	$ 36,557	$ 33,846	$ 34,677