Schedule I - Condensed Financial Information of Registrant - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended	11 Months Ended		12 Months Ended
	May 31, 2019	Nov. 30, 2018	Nov. 30, 2017	Nov. 30, 2019	Dec. 31, 2017
Adjustments to reconcile net income to net cash provided by (used for) operations:
Deferred income tax provision (benefit)		$ 236,406		$ 6,391	$ 712,055
Recognition of accumulated other comprehensive income lodged taxes	$ (544,600)	0		(544,583)	0
Share-based compensation		48,249		49,848	48,384
Income related to associated companies		(57,023)	$ 76,864	(202,995)	74,901
Distributions from associated companies		162,988		467,157	143,286
Net change in:
Trading assets		(1,451,472)		218,419	(648,703)
Other assets		33,484		15,705	(8,102)
Other		(124,580)		61,565	(25,838)
Net cash provided by (used for) operating activities		691,103		(827,837)	788,294
Net cash flows from investing activities:
Proceeds from sale of associated companies		379,074		790,612	173,105
Investments in associated companies		(1,956,983)		(267,263)	(3,305,791)
Purchases of investments (other than short-term)		(3,423,191)		(2,995)	(1,146,595)
Other		130		0	1,339
Net cash provided by (used for) investing activities - continuing operations		(718,466)		1,707,095	12,771
Net cash provided by (used for) investing activities - discontinued operations		860,909		0	(67,405)
Net cash provided by (used for) investing activities		142,443		1,707,095	(54,634)
Net cash flows from financing activities:
Issuance of common shares		3,611		1,112	1,501
Purchase of common shares for treasury		(1,130,854)		(509,914)	(100,477)
Dividends paid		(151,758)		(149,647)	(117,407)
Net cash provided by (used for) financing activities		(575,843)		1,589,578	434,801
Net increase in cash, cash equivalents and restricted cash		238,157		2,467,773	1,177,392
Cash, cash equivalents and restricted cash at beginning of period		5,774,505	4,597,113	6,012,662	4,597,113
Cash, cash equivalents and restricted cash at end of period		6,012,662		8,480,435	5,774,505
Parent Company
Net cash flows from operating activities:
Net income		1,026,788		964,696	171,726
Adjustments to reconcile net income to net cash provided by (used for) operations:
Deferred income tax provision (benefit)		142,085		(12,953)	116,942
Recognition of accumulated other comprehensive income lodged taxes		0		(544,583)	0
Accretion of interest		944		1,088	975
Share-based compensation		48,249		49,848	48,384
Equity in earnings of subsidiaries, including equity in earnings of discontinued operations		(291,239)		(343,588)	(622,320)
Gain on disposal of discontinued operation		(873,474)		0	0
Income related to associated companies		(96,808)		(229,320)	(3,183)
Distributions from associated companies		24,711		319,142	5,641
Gains on sale/revaluation of associated companies		0		(254,875)	0
Net change in:
Trading assets		(120,886)		196,245	22,415
Other assets		129		376	1,250
Accrued interest payable		(4,818)		0	0
Pension liabilities		(5,231)		(5,062)	(8,461)
Other payables, expense accruals and other liabilities		(1,712)		(5,260)	(7,763)
Income taxes receivable/payable, net		242,637		94,510	(164,684)
Other		6,315		3,770	2,316
Net cash provided by (used for) operating activities		97,690		234,034	(436,762)
Net cash flows from investing activities:
Distributions (to) from subsidiaries, net		38,304		(388,739)	50,122
Proceeds from sale of associated companies		0		790,612	0
Investments in associated companies		(1,228)		(51,622)	(45,457)
Capital distributions from associated companies		24,442		32,612	2,796
Purchases of investments (other than short-term)		(1,500)		0	(1,316)
Other		0		(948)	1,886
Net cash provided by (used for) investing activities - continuing operations		60,018		381,915	8,031
Net cash provided by (used for) investing activities - discontinued operations		1,158,655		0	337,690
Net cash provided by (used for) investing activities		1,218,673		381,915	345,721
Net cash flows from financing activities:
Advances (to) from subsidiaries, net		(1,139)		(2,487)	214,519
Issuance of common shares		3,611		1,112	1,501
Purchase of common shares for treasury		(1,130,854)		(509,914)	(100,477)
Dividends paid		(151,758)		(149,647)	(117,407)
Net cash provided by (used for) financing activities		(1,280,140)		(660,936)	(1,864)
Net increase in cash, cash equivalents and restricted cash		36,223		(44,987)	(92,905)
Cash, cash equivalents and restricted cash at beginning of period		12,317	$ 105,222	48,540	105,222
Cash, cash equivalents and restricted cash at end of period		$ 48,540		$ 3,553	$ 12,317