Related Party Transactions - Jefferies (Details) - USD ($)			3 Months Ended		9 Months Ended	12 Months Ended
	Nov. 27, 2019	Oct. 01, 2018	Nov. 30, 2019	Nov. 30, 2018	Aug. 31, 2019	Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2017	Oct. 31, 2018
Related Party Transaction [Line Items]
Goodwill			$ 1,643,599,000	$ 1,642,170,000	$ 1,643,600,000	$ 1,643,599,000	$ 1,642,170,000	$ 1,647,089,000
Intangible assets			170,542,000	182,468,000		170,542,000	182,468,000
Payables to brokers, dealers and clearing organizations			2,555,178,000	2,448,059,000		2,555,178,000	2,448,059,000
Financial instruments sold, not yet purchased, at fair value			10,532,460,000	9,478,944,000		10,532,460,000	9,478,944,000
Financial instruments owned, at fair value			16,363,374,000	16,399,526,000		16,363,374,000	16,399,526,000
Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Charges to Jefferies for services provided						52,700,000	61,200,000	42,200,000
Charges from Jefferies for services received						9,500,000	9,100,000	14,200,000
Receivable from Jefferies			900,000	1,200,000		900,000	1,200,000
Payable to Jefferies			4,300,000	2,900,000		4,300,000	2,900,000
Payments of distributions						311,100,000	248,700,000
Accrued distributions payable						12,600,000	30,700,000
Tax receivable			24,400,000			24,400,000
Tax payable				34,100,000			34,100,000
Payment made to related party related to tax sharing agreement				70,500,000		71,400,000	193,000,000.0
Payment received for transferred investment	$ 31,000,000.0
Sale of debt securities						110,900,000
Related party transaction, related deferred tax liabilities transferred		$ 50,900,000	3,100,000			3,100,000
Payments to acquire investments						917,200,000
Net gains on our investments					$ 0
Capital contribution from Jefferies		$ 598,200,000
Entity net book value									$ 5,500,000
Goodwill									400,000
Intangible assets									$ 200,000
Payables to brokers, dealers and clearing organizations				9,900,000			9,900,000
Jefferies | Affiliated Entity | Investment banking
Related Party Transaction [Line Items]
Charges to Jefferies for services provided						10,600,000	15,700,000	14,700,000
Jefferies | Affiliated Entity | Commissions and other fees
Related Party Transaction [Line Items]
Charges to Jefferies for services provided						1,200,000	1,800,000	300,000
Jefferies | Affiliated Entity | Principal transactions
Related Party Transaction [Line Items]
Charges to Jefferies for services provided						0	100,000	0
Affiliate of Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Payables to brokers, dealers and clearing organizations			9,900,000			9,900,000
Subsidiary of Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Financial instruments sold, not yet purchased, at fair value			600,000			600,000
Loss on derivative						6,100,000
Hedge Fund Managed By Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Net gains on our investments						4,700,000	5,000,000.0	$ 8,000,000.0
Investment in related party			223,500,000	218,700,000		223,500,000	218,700,000
Corporate debt securities
Related Party Transaction [Line Items]
Financial instruments sold, not yet purchased, at fair value			1,471,482,000	1,506,140,000		1,471,482,000	1,506,140,000
Financial instruments owned, at fair value			2,479,703,000	2,692,664,000		2,479,703,000	2,692,664,000
Corporate debt securities | Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Financial instruments owned, at fair value			100,000	300,000		100,000	300,000
Director | Affiliated Entity
Related Party Transaction [Line Items]
Investment in related party			3,600,000	4,600,000		3,600,000	4,600,000
Director | Hedge Fund Managed By Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Investment in related party			400,000	$ 2,700,000		$ 400,000	$ 2,700,000
Berkadia | Jefferies | Affiliated Entity
Related Party Transaction [Line Items]
Ownership percentage		50.00%
Related party transaction, related deferred tax liabilities transferred, adjustment			$ 19,100,000