Schedule I - Condensed Financial Information of Registrant - Condensed Statements of Financial Condition, Additional Information (Details) - $ / shares	Nov. 30, 2019	Nov. 30, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Common shares, par value (USD per share)	$ 1	$ 1	$ 1
Common shares, authorized (in shares)	600,000,000	600,000,000
Common shares, issued and outstanding after deducting shares held in treasury (in shares)	291,644,153	307,515,472
Treasury stock, shares (in shares)	24,818,459	109,460,774
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Common shares, par value (USD per share)	$ 1	$ 1
Common shares, authorized (in shares)	600,000,000	600,000,000
Common shares, issued and outstanding after deducting shares held in treasury (in shares)	291,644,153	307,515,472
Treasury stock, shares (in shares)	24,818,459	109,460,774