Other Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Assets Details [Abstract]
Goodwill	$ 3,009.0	$ 2,927.0	$ 2,749.0
Deferred Tax Assets, Net	1,647.0	2,336.0
Prepaid expenses	684.0	696.0
Other intangible assets, at amortized cost	899.0	868.0
Community Reinvestment Act Tax Credit Investments	1,023.0	824.0
Restricted cash	336.0	286.0
Derivative assets	124.0	555.0
Other	2,033.0	2,069.0
Other assets	$ 9,755.0	$ 10,561.0