Goodwill, Customer Relationships and Other Intangible Assets Goodwill, Customer Relationships and Other Intangible Assets (Details 3) $ in Millions				12 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Sep. 30, 2013	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Goodwill [Line Items]
Percentage of reasonable implied control premium (percent)				24.60%
Number of reporting units	3	4	1
Impairment of goodwill				$ 0	$ 0	$ 1,092
Consumer and Wholesale reportable units
Goodwill [Line Items]
Discount rate (percent)	6.00%
Fair value inputs after tax cost of debt rate (percent)	3.30%
Fair value inputs cost of equity rate (percent)	7.60%
Business reporting unit
Goodwill [Line Items]
Discount rate (percent)	7.00%
Fair value inputs after tax cost of debt rate (percent)	3.30%
Fair value inputs cost of equity rate (percent)	8.60%