Commitments, Contingencies And Guarantees (Commitments And Contingencies) (Details) $ in Millions	Jun. 30, 2015 USD ($)
Commitments And Guarantee Obligations [Line Items]
2015	$ 3,395.5
2016	1,815.5
2017 and 2018	887.4
2019 and 2020	66.1
2021 and Later	295.2
Maximum Payout	6,459.7
Equity Commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	0.0
2016	9.2
2017 and 2018	0.9
2019 and 2020	0.0
2021 and Later	257.7
Maximum Payout	267.8
Loan Commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	34.3
2016	475.7
2017 and 2018	387.4
2019 and 2020	60.1
2021 and Later	0.0
Maximum Payout	957.5
Mortgage-Related And Other Purchase Commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	909.9
2016	1,330.6
2017 and 2018	499.1
2019 and 2020	0.0
2021 and Later	0.0
Maximum Payout	2,739.6
Underwriting Commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	36.9
2016	0.0
2017 and 2018	0.0
2019 and 2020	0.0
2021 and Later	0.0
Maximum Payout	36.9
Forward Starting Reverse Repos And Repos [Member]
Commitments And Guarantee Obligations [Line Items]
2015	2,384.4
2016	0.0
2017 and 2018	0.0
2019 and 2020	0.0
2021 and Later	0.0
Maximum Payout	2,384.4
Other Unfunded Commitments [Member]
Commitments And Guarantee Obligations [Line Items]
2015	30.0
2016	0.0
2017 and 2018	0.0
2019 and 2020	6.0
2021 and Later	37.5
Maximum Payout	$ 73.5