Variable Interest Entities (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Variable Interest Entity [Line Items]
Other operating activities, net				$ 330,200,000	$ (230,300,000)
Investment Funds
Variable Interest Entity [Line Items]
Exposure to loss from liquidity arrangements and obligations to purchase assets		$ 0		0
Pre-tax charge	$ 45,800,000
Investment Funds | Constant Dollar Net Asset Value Investment Funds
Variable Interest Entity [Line Items]
Other operating activities, net	$ 45,800,000
Net assets held by the funds		1.00		1.00
Tax Credit Structures
Variable Interest Entity [Line Items]
Carrying amounts		176,400,000		176,400,000		$ 208,900,000
Exposure to loss from liquidity arrangements and obligations to purchase assets		0		0
Liabilities related to undrawn commitments		12,100,000		12,100,000		15,600,000
Affordable housing tax credits and other tax benefits		13,100,000	$ 14,500,000	39,600,000	$ 43,200,000
Leveraged Leasing Transactions
Variable Interest Entity [Line Items]
Carrying amounts		496,300,000		496,300,000		$ 547,600,000
Exposure to loss from liquidity arrangements and obligations to purchase assets		$ 0		$ 0
Leveraged Leasing Transactions | Lower Limit
Variable Interest Entity [Line Items]
Funding of asset's cost via an equity interest		20.00%		20.00%
Funding of asset's cost via third party non recourse debt holders		70.00%		70.00%
Leveraged Leasing Transactions | Upper Limit
Variable Interest Entity [Line Items]
Funding of asset's cost via an equity interest		30.00%		30.00%
Funding of asset's cost via third party non recourse debt holders		80.00%		80.00%