Commitments and Contingent Liabilities (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Guarantor Obligations
Guarantor obligations, maximum exposure, undiscounted		$ 4,932.0	$ 4,603.6
Indirect guarantee of indebtedness
Guarantor Obligations
Guarantor obligations, term of obligation		P5Y
Financial guarantees
Guarantor Obligations
Guarantor obligations, maximum exposure, undiscounted	[1]	$ 830.7	933.3
Performance guarantees
Guarantor Obligations
Guarantor obligations, maximum exposure, undiscounted	[2]	$ 4,101.3	$ 3,670.3

[1] Financial guarantees represent contracts that contingently require a guarantor to make payments to a guaranteed party based on changes in an underlying agreement that is related to an asset, a liability or an equity security of the guaranteed party. These tend to be drawn down only if there is a failure to fulfill our financial obligations.

[2] Performance guarantees represent contracts that contingently require a guarantor to make payments to a guaranteed party based on another entity's failure to perform under a nonfinancial obligating agreement. Events that trigger payment are performance-related, such as failure to ship a product or provide a service.