Premises and Equipment - Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Other Assets
Other investments	$ 2,953	$ 2,695
Software	364	275
Intangible assets	206	240
OREO	31	36
Other	1,823	1,384
Total other assets	$ 5,377	$ 4,630