Summary of Significant Accounting Policies Fee and Other Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Gain Contingencies [Line Items]
Fee and other income	$ 225	$ 259	$ 556	$ 308	$ 323	$ 826	$ 383	$ 4,355	$ 1,348	$ 5,887	$ 3,930
Private Label Securities Settlements [Member]
Gain Contingencies [Line Items]
Fee and other income									$ 21	$ 4,800	$ 2,200