Commitments, Contingencies and Guarantees - Commitments (Detail) $ in Millions	Feb. 28, 2019 USD ($)
Commitments and Guarantees Obligations [Line Items]
2019	$ 11,595.1
2020	145.2
2021 and 2022	145.2
2023 and 2024	34.9
2025 and Later	502.9
Maximum Payout	12,423.3
Equity commitments
Commitments and Guarantees Obligations [Line Items]
2019	0.0
2020	145.2
2021 and 2022	0.3
2023 and 2024	0.0
2025 and Later	2.9
Maximum Payout	148.4
Loan commitments
Commitments and Guarantees Obligations [Line Items]
2019	250.0
2020	0.0
2021 and 2022	54.0
2023 and 2024	30.0
2025 and Later	500.0
Maximum Payout	834.0
Underwriting commitments
Commitments and Guarantees Obligations [Line Items]
2019	215.4
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	215.4
Forward starting reverse repos
Commitments and Guarantees Obligations [Line Items]
2019	6,225.6
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	6,225.6
Forward starting repos
Commitments and Guarantees Obligations [Line Items]
2019	4,738.8
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	4,738.8
Other unfunded commitments
Commitments and Guarantees Obligations [Line Items]
2019	165.3
2020	0.0
2021 and 2022	90.9
2023 and 2024	4.9
2025 and Later	0.0
Maximum Payout	261.1
Forward starting securities purchased under agreements to resell settled within three business days
Commitments and Guarantees Obligations [Line Items]
Maximum Payout	6,225.4
Forward starting securities purchased under agreements to repurchase settled within three business days
Commitments and Guarantees Obligations [Line Items]
Maximum Payout	$ 4,736.0