Commitments, Contingencies And Guarantees (Commitments And Contingencies) (Details) $ in Millions	Dec. 31, 2015 USD ($)
Guarantor Obligations [Line Items]
2016	$ 3,647.5
2017	695.4
2018 and 2019	1,159.2
2020 and 2021	41.6
2022 and Later	225.1
Maximum Payout	5,768.8
Equity Commitments [Member]
Guarantor Obligations [Line Items]
2016	106.8
2017	25.3
2018 and 2019	43.9
2020 and 2021	35.9
2022 and Later	189.5
Maximum Payout	401.4
Loan Commitments [Member]
Guarantor Obligations [Line Items]
2016	247.3
2017	170.7
2018 and 2019	81.4
2020 and 2021	0.0
2022 and Later	0.0
Maximum Payout	499.4
Mortgage Related and Other Purchase Commitments [Member]
Guarantor Obligations [Line Items]
2016	1,571.4
2017	312.5
2018 and 2019	1,013.7
2020 and 2021	0.0
2022 and Later	0.0
Maximum Payout	2,897.6
Forward Starting Reverse Repos And Repos [Member]
Guarantor Obligations [Line Items]
2016	1,635.0
2017	0.0
2018 and 2019	0.0
2020 and 2021	0.0
2022 and Later	0.0
Maximum Payout	1,635.0
Other Unfunded Commitments [Member]
Guarantor Obligations [Line Items]
2016	87.0
2017	186.9
2018 and 2019	20.2
2020 and 2021	5.7
2022 and Later	35.6
Maximum Payout	$ 335.4