Commitments, Contingencies and Guarantees - Commitments and Contingencies (Detail) $ in Millions	9 Months Ended
	Aug. 31, 2017 USD ($)
Other Commitments [Line Items]
2017	$ 6,076.7
2018	390.7
2019 and 2020	318.5
2021 and 2022	279.2
2023 and Later	217.4
Maximum Payout	$ 7,282.5
Guarantor obligation settled period (in days)	3 days
Equity commitments
Other Commitments [Line Items]
2017	$ 0.0
2018	9.4
2019 and 2020	10.2
2021 and 2022	0.0
2023 and Later	205.3
Maximum Payout	224.9
Loan commitments
Other Commitments [Line Items]
2017	0.0
2018	226.8
2019 and 2020	0.0
2021 and 2022	53.0
2023 and Later	0.0
Maximum Payout	279.8
Mortgage-related and other purchase commitments
Other Commitments [Line Items]
2017	0.0
2018	0.0
2019 and 2020	177.7
2021 and 2022	0.0
2023 and Later	0.0
Maximum Payout	177.7
Underwriting commitments
Other Commitments [Line Items]
2017	70.0
2018	0.0
2019 and 2020	0.0
2021 and 2022	0.0
2023 and Later	0.0
Maximum Payout	70.0
Forward starting reverse repos
Other Commitments [Line Items]
2017	3,943.7
2018	0.0
2019 and 2020	0.0
2021 and 2022	0.0
2023 and Later	0.0
Maximum Payout	3,943.7
Forward starting repos
Other Commitments [Line Items]
2017	2,018.0
2018	0.0
2019 and 2020	0.0
2021 and 2022	0.0
2023 and Later	0.0
Maximum Payout	2,018.0
Other unfunded commitments
Other Commitments [Line Items]
2017	45.0
2018	154.5
2019 and 2020	130.6
2021 and 2022	226.2
2023 and Later	12.1
Maximum Payout	$ 568.4