Loans and Allowance for Credit Losses, Loans by FICO Score, Consumer (Details) - USD ($) $ in Millions	Sep. 30, 2015		Dec. 31, 2014	Dec. 31, 2008
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	$ 20,737		$ 23,320
Loans	903,233	[1]	862,551
Total Consumer [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	19,960		21,813	$ 40,100
Loans	455,895		447,725
Real estate 1-4 family first mortgage [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	19,885		21,712
Loans	271,311		265,386
Real estate 1-4 family junior lien mortgage [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	75		101
Loans	54,592		59,717
Credit Card [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	0		0
Loans	32,286		31,119
Automobile [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	0		0
Loans	59,164		55,740
Other revolving credit and installment [Member]
By updated FICO:
Purchased Credit Impaired Loans (carrying value)	0		0
Loans	38,542		35,763
Loans Excluding Purchased Credit-Impaired Loans [Member] | Total Consumer [Member]
By updated FICO:
Less than 600	25,284		27,525
600-639	20,156		20,542
640-679	35,690		35,867
680-719	54,661		54,050
720-759	69,239		67,439
760-799	129,841		120,242
800 and greater	64,139		61,561
No FICO available	7,435		6,564
FICO not required	6,727		5,854
Government insured/guaranteed loans	22,763		26,268
Loans, excluding Purchased Credit Impaired Loans	435,935		425,912
Loans Excluding Purchased Credit-Impaired Loans [Member] | Real estate 1-4 family first mortgage [Member]
By updated FICO:
Less than 600	9,459		11,166
600-639	7,210		7,866
640-679	13,416		13,894
680-719	24,678		24,412
720-759	37,147		35,490
760-799	91,670		82,123
800 and greater	41,613		39,219
No FICO available	3,470		3,236
FICO not required	0		0
Government insured/guaranteed loans	22,763		26,268
Loans, excluding Purchased Credit Impaired Loans	251,426		243,674
Loans Excluding Purchased Credit-Impaired Loans [Member] | Real estate 1-4 family junior lien mortgage [Member]
By updated FICO:
Less than 600	3,163		4,001
600-639	2,484		2,794
640-679	4,806		5,324
680-719	8,176		8,970
720-759	11,327		12,171
760-799	16,802		17,897
800 and greater	6,892		7,581
No FICO available	867		878
FICO not required	0		0
Government insured/guaranteed loans	0		0
Loans, excluding Purchased Credit Impaired Loans	54,517		59,616
Loans Excluding Purchased Credit-Impaired Loans [Member] | Credit Card [Member]
By updated FICO:
Less than 600	2,799		2,639
600-639	2,760		2,588
640-679	5,128		4,931
680-719	6,540		6,285
720-759	6,673		6,407
760-799	5,386		5,234
800 and greater	2,767		2,758
No FICO available	233		277
FICO not required	0		0
Government insured/guaranteed loans	0		0
Loans, excluding Purchased Credit Impaired Loans	32,286		31,119
Loans Excluding Purchased Credit-Impaired Loans [Member] | Automobile [Member]
By updated FICO:
Less than 600	8,945		8,825
600-639	6,633		6,236
640-679	10,003		9,352
680-719	10,871		9,994
720-759	8,149		7,475
760-799	7,687		7,315
800 and greater	6,461		6,184
No FICO available	415		359
FICO not required	0		0
Government insured/guaranteed loans	0		0
Loans, excluding Purchased Credit Impaired Loans	59,164		55,740
Loans Excluding Purchased Credit-Impaired Loans [Member] | Other revolving credit and installment [Member]
By updated FICO:
Less than 600	918		894
600-639	1,069		1,058
640-679	2,337		2,366
680-719	4,396		4,389
720-759	5,943		5,896
760-799	8,296		7,673
800 and greater	6,406		5,819
No FICO available	2,450		1,814
FICO not required	6,727		5,854
Government insured/guaranteed loans	0		0
Loans, excluding Purchased Credit Impaired Loans	$ 38,542		$ 35,763

[1] Parenthetical amounts represent assets and liabilities for which we have elected the fair value option.