Commitments, Contingencies and Guarantees - Commitments (Details) $ in Millions	Aug. 31, 2019 USD ($)
Commitments and Guarantees Obligations [Line Items]
2019	$ 7,189.0
2020	373.5
2021 and 2022	197.8
2023 and 2024	12.0
2025 and Later	16.4
Maximum Payout	7,788.7
Equity commitments
Commitments and Guarantees Obligations [Line Items]
2019	0.0
2020	123.5
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	11.5
Maximum Payout	135.0
Loan commitments
Commitments and Guarantees Obligations [Line Items]
2019	0.0
2020	250.0
2021 and 2022	54.1
2023 and 2024	12.0
2025 and Later	0.0
Maximum Payout	316.1
Underwriting commitments
Commitments and Guarantees Obligations [Line Items]
2019	31.5
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	31.5
Forward starting reverse repos
Commitments and Guarantees Obligations [Line Items]
2019	2,994.6
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	2,994.6
Forward starting repos
Commitments and Guarantees Obligations [Line Items]
2019	4,082.9
2020	0.0
2021 and 2022	0.0
2023 and 2024	0.0
2025 and Later	0.0
Maximum Payout	4,082.9
Other unfunded commitments
Commitments and Guarantees Obligations [Line Items]
2019	80.0
2020	0.0
2021 and 2022	143.7
2023 and 2024	0.0
2025 and Later	4.9
Maximum Payout	228.6
Forward starting securities purchased under agreements to resell settled within three business days
Commitments and Guarantees Obligations [Line Items]
Maximum Payout	$ 2,991.6