Goodwill and Other Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2018	Aug. 31, 2018	Nov. 30, 2017
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)		$ 9
Goodwill	$ 1,643,058	1,643,058	$ 1,647,089
Total gross costs - intangible assets	262,864	262,864	264,333
Accumulated amortization - finite lived intangible assets	(77,134)	(77,134)	(68,540)
Total net carrying amount - intangible assets	185,721	185,721	195,793
Exchange and clearing organization membership interests and registrations
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	9	9
Gross costs - indefinite lived intangible assets	8,484	8,484	8,551
Net carrying amount - indefinite lived intangible assets	8,475	8,475	8,551
Customer relationships
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items]
Gross costs - finite lived intangible assets	125,763	125,763	126,412
Accumulated amortization - finite lived intangible assets	(56,923)	(56,923)	(50,983)
Net carrying amount - finite lived intangible assets	68,840	$ 68,840	$ 75,429
Weighted average remaining lives (years)		10 years 8 months	11 years 3 months
Trade name
Schedule of Finite-Lived and Indefinite-Lived Intangible Assets [Table] [Line Items]
Gross costs - finite lived intangible assets	128,617	$ 128,617	$ 129,370
Accumulated amortization - finite lived intangible assets	(20,211)	(20,211)	(17,557)
Net carrying amount - finite lived intangible assets	$ 108,406	$ 108,406	$ 111,813
Weighted average remaining lives (years)		29 years 6 months	30 years 3 months