Offsetting of Assets and Liabilities (Offsetting of Derivative Liabilities and Securities Sold Under Agreements to Repurchase) (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Offsetting Liabilities [Line Items]
Gross recognized liabilities, total derivatives subject to a master netting arrangement	$ 4,119,200,000	$ 2,261,800,000
Gross amounts offset, total derivatives subject to a master netting arrangement	3,778,300,000	1,717,600,000
Net amounts presented, total derivatives subject to a master netting arrangement	340,900,000	544,200,000
Net amount, total derivatives subject to a master netting arrangement	340,900,000	544,200,000
Total Derivatives Not Subject to a Master Netting Arrangement	874,200,000	399,700,000
Gross recognized liabilities, total derivatives	4,993,400,000	2,661,500,000
Net amount, total derivatives	1,215,100,000	943,900,000
Gross recognized liabilities, securities sold under agreements to repurchase	565,500,000	546,600,000
Net amounts presented, securities sold under agreements to repurchase	565,500,000	546,600,000
Gross amounts not offset, securities sold under agreements to repurchase	565,500,000	546,600,000
Other liabilities	2,200,000,000	2,100,000,000
Cash collateral possessed that was not offset	0	0
Foreign Exchange Contracts | Over the Counter Derivative
Offsetting Liabilities [Line Items]
Gross recognized liabilities, total derivatives subject to a master netting arrangement	3,821,000,000	2,119,700,000
Gross amounts offset, total derivatives subject to a master netting arrangement	2,107,200,000	1,194,300,000
Net amounts presented, total derivatives subject to a master netting arrangement	1,713,800,000	925,400,000
Net amount, total derivatives subject to a master netting arrangement	1,713,800,000	925,400,000
Interest Rate Swap Contracts | Over the Counter Derivative
Offsetting Liabilities [Line Items]
Gross recognized liabilities, total derivatives subject to a master netting arrangement	133,000,000	93,100,000
Gross amounts offset, total derivatives subject to a master netting arrangement	23,100,000	21,500,000
Net amounts presented, total derivatives subject to a master netting arrangement	109,900,000	71,600,000
Net amount, total derivatives subject to a master netting arrangement	109,900,000	71,600,000
Interest Rate Swap Contracts | Exchange Cleared
Offsetting Liabilities [Line Items]
Gross recognized liabilities, total derivatives subject to a master netting arrangement	136,400,000	38,100,000
Gross amounts offset, total derivatives subject to a master netting arrangement	136,400,000	38,100,000
Other Financial Derivatives
Offsetting Liabilities [Line Items]
Gross recognized liabilities, total derivatives subject to a master netting arrangement	28,800,000	10,900,000
Net amounts presented, total derivatives subject to a master netting arrangement	28,800,000	10,900,000
Net amount, total derivatives subject to a master netting arrangement	28,800,000	10,900,000
Cross Product Netting Adjustment
Offsetting Liabilities [Line Items]
Gross amounts offset, total derivatives subject to a master netting arrangement	133,900,000	23,500,000
Cross Product Collateral Adjustment
Offsetting Liabilities [Line Items]
Gross amounts offset, total derivatives subject to a master netting arrangement	$ 1,377,700,000	$ 440,200,000