Fair Value Disclosures (Financial Instruments Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Feb. 29, 2020	Nov. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and securities segregated under federal and other regulations	$ 742,134	$ 796,797
US treasury securities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and securities segregated under federal and other regulations	$ 331,500	$ 35,000

Amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 305
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6478312&loc=d3e61473-112792

Name:	us-gaap_CashAndSecuritiesSegregatedUnderFederalAndOtherRegulations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant