Loans and Allowance for Credit Losses, Loans Outstanding (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	[1]	$ 949,878	$ 953,110
Deferred income as a percent of loans		1.00%	1.00%
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 512,245	$ 513,405
Commercial and industrial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		348,846	350,199
Commercial real estate mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		123,008	121,014
Commercial real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		21,067	22,496
Commercial lease financing receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		19,324	19,696
Total Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		437,633	439,705
Real estate 1-4 family first mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		286,427	285,065
Real estate 1-4 family junior lien mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		32,068	34,398
Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		38,820	39,025
Automobile [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		45,664	45,069
Other revolving credit and installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		34,654	36,148
Geographic Distribution, Foreign [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		72,599	71,465
Geographic Distribution, Foreign [Member] | Commercial and industrial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		63,296	62,564
Geographic Distribution, Foreign [Member] | Commercial real estate mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		6,801	6,731
Geographic Distribution, Foreign [Member] | Commercial real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		1,287	1,011
Geographic Distribution, Foreign [Member] | Commercial lease financing receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans		$ 1,215	$ 1,159

[1] (1) Parenthetical amounts represent assets and liabilities that we are required to carry at fair value or have elected the fair value option.