Commitments, Contingencies and Guarantees - Commitments (Details) $ in Millions	May 31, 2020 USD ($)
Commitments and Guarantees Obligations [Line Items]
2020	$ 7,435.4
2021	510.4
2022 and 2023	35.0
2024 and 2025	4.9
2026 and Later	7.7
Maximum Payout	7,993.4
Equity commitments
Commitments and Guarantees Obligations [Line Items]
2020	29.3
2021	99.0
2022 and 2023	0.0
2024 and 2025	0.0
2026 and Later	7.7
Maximum Payout	136.0
Loan commitments
Commitments and Guarantees Obligations [Line Items]
2020	0.0
2021	275.0
2022 and 2023	35.0
2024 and 2025	0.0
2026 and Later	0.0
Maximum Payout	310.0
Underwriting commitments
Commitments and Guarantees Obligations [Line Items]
2020	58.0
2021	0.0
2022 and 2023	0.0
2024 and 2025	0.0
2026 and Later	0.0
Maximum Payout	58.0
Forward starting reverse repos
Commitments and Guarantees Obligations [Line Items]
2020	3,300.0
2021	0.0
2022 and 2023	0.0
2024 and 2025	0.0
2026 and Later	0.0
Maximum Payout	3,300.0
Forward starting repos
Commitments and Guarantees Obligations [Line Items]
2020	4,048.1
2021	0.0
2022 and 2023	0.0
2024 and 2025	0.0
2026 and Later	0.0
Maximum Payout	4,048.1
Other unfunded commitments
Commitments and Guarantees Obligations [Line Items]
2020	0.0
2021	136.4
2022 and 2023	0.0
2024 and 2025	4.9
2026 and Later	0.0
Maximum Payout	$ 141.3