Loans - Consumer, Excluding Credit Card Loans, Delinquency Statistics Junior Lien Home Equity Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 969,415	$ 924,838	$ 889,907
Consumer, excluding credit card
Loans and Leases Receivable Disclosure [Line Items]
Loans	373,637	372,553	$ 364,406
Consumer, excluding credit card | Total
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 28,340	$ 33,450
Total 30 plus day delinquency rate	2.57%	3.17%
Consumer, excluding credit card | HELOCs | Within the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Open-ended revolving period	10 years
Consumer, excluding credit card | HELOCs | Beyond the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Amortization period	20 years
Consumer, excluding credit card | Senior lien | Total
Loans and Leases Receivable Disclosure [Line Items]
Percentage of senior liens to total financing receivables	37.00%
Consumer, excluding credit card | Junior lien | Total
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 17,924	$ 21,266
Total 30 plus day delinquency rate	2.00%	2.64%
Consumer, excluding credit card | Junior lien | HELOCs | Within the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 5,608	$ 6,363
Total 30 plus day delinquency rate	0.25%	0.50%
Consumer, excluding credit card | Junior lien | HELOCs | Beyond the revolving period
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 11,286	$ 13,532
Total 30 plus day delinquency rate	2.80%	3.56%
Consumer, excluding credit card | Junior lien | HELOANs
Loans and Leases Receivable Disclosure [Line Items]
Loans	$ 1,030	$ 1,371
Total 30 plus day delinquency rate	2.82%	3.50%