Litigation, Other Commitments and Contingencies, and Disclosures about Guarantees, Other Commitments (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Dec. 31, 2008
Other Commitments [Abstract]
Membership interest in U.S Bank New Markets Tax Credit Fund (in hundredths)			99.90%
Equity contributions to be made to the Fund	$ 285.5
Net tax benefits and cash to be received from the Fund	303.8
Difference between equity contributions and total benefits received	18.3
Liability component contained in the net asset		$ 0.6
Tax Benefits in Excess of Capital Contributions	$ 11.1
Period of recognition of gross investment amortization expense (in years)	10 years