Basis of Presentation and Significant Accounting Policies (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	May 31, 2020	Nov. 30, 2019	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019	Dec. 01, 2019
Loans and Leases Receivable Disclosure [Line Items]
Revenues			$ 1,377,531	$ 1,510,371	$ 3,069,795	$ 2,705,383
Receivables from brokers, dealers and clearing organizations	$ 4,211,700	$ 3,011,000	4,211,700		4,211,700
Receivables from customers of securities operations	1,077,400	1,490,900	1,077,400		1,077,400
Other investments with fair values not readily determinable	123,100	172,800	123,100		123,100
Impairment losses on investments			600	0	20,600	0
Capitalized interest			1,900		3,900
Payables to brokers, dealers and clearing organizations	3,006,500	2,621,700	3,006,500		3,006,500
Payables to customers of securities operations	3,655,500	3,808,600	3,655,500		3,655,500
Cash paid during the year for:
Interest					584,009	808,740
Income tax payments (refunds), net					(5,330)	21,410
Lease liabilities	597,267		597,267		597,267
Accounting standards update 2016-02
Cash paid during the year for:
Operating lease, ROU assets							$ 545,800
Lease liabilities							$ 614,900
Commissions and other fees
Loans and Leases Receivable Disclosure [Line Items]
Revenues			242,972	167,610	422,402	322,560
Other
Loans and Leases Receivable Disclosure [Line Items]
Revenues			31,619	136,281	143,614	182,296
Foursight Capital | Automobile Loan
Loans and Leases Receivable Disclosure [Line Items]
Loans receivable	$ 753,000	$ 741,200	753,000		753,000
Foursight Capital | Automobile Loan | Credit concentration risk | Loans receivable | Prime
Loans and Leases Receivable Disclosure [Line Items]
Concentration risk, percentage	14.00%	15.00%
Foursight Capital | Automobile Loan | Credit concentration risk | Loans receivable | Near-Prime
Loans and Leases Receivable Disclosure [Line Items]
Concentration risk, percentage	53.00%	53.00%
Foursight Capital | Automobile Loan | Credit concentration risk | Loans receivable | Subprime
Loans and Leases Receivable Disclosure [Line Items]
Concentration risk, percentage	33.00%	32.00%
Foursight Capital | Securitized Vehicles
Loans and Leases Receivable Disclosure [Line Items]
Loans receivable	$ 670,300	$ 621,200	$ 670,300		$ 670,300
Reclassified presentation of certain other fees | Jefferies Group | Commissions and other fees
Loans and Leases Receivable Disclosure [Line Items]
Revenues				7,900		15,700
Reclassified presentation of certain other fees | Jefferies Group | Other
Loans and Leases Receivable Disclosure [Line Items]
Revenues				$ (7,900)		$ (15,700)