Commitments, Contingencies And Guarantees (Guarantees) (Details) $ in Millions	Mar. 31, 2017 USD ($)
Guarantee Obligations [Line Items]
Maximum Payout	$ 7,234.4
Derivative Contracts - Non-Credit Related [Member] | Derivative Notional Amount [Member]
Guarantee Obligations [Line Items]
2017	17,839.8
2018	1,562.1
2019 and 2020	0.0
2021 and 2022	0.0
2023 and Later	421.7
Maximum Payout	19,823.6
Written Derivative Contracts - Credit Related [Member] | Derivative Notional Amount [Member]
Guarantee Obligations [Line Items]
2017	0.0
2018	53.4
2019 and 2020	11.5
2021 and 2022	294.3
2023 and Later	0.0
Maximum Payout	359.2
Derivative [Member] | Derivative Notional Amount [Member]
Guarantee Obligations [Line Items]
2017	17,839.8
2018	1,615.5
2019 and 2020	11.5
2021 and 2022	294.3
2023 and Later	421.7
Maximum Payout	$ 20,182.8