Loans and Allowance for Loan Losses (Details 9) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Consumer
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 30,357	$ 31,712
Percentage of total loans categorized by LTV ratio		100.00%	100.00%
Consumer | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 28,971	$ 29,657
Percentage of total loans categorized by LTV ratio		95.00%	94.00%
Consumer | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 1,103	$ 1,745
Percentage of total loans categorized by LTV ratio		4.00%	5.00%
Consumer | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 157	$ 228
Percentage of total loans categorized by LTV ratio		1.00%	1.00%
Consumer | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 126	$ 82	[1]
Percentage of total loans categorized by LTV ratio		0.00%	0.00%
Consumer portfolio
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 30,200	$ 31,517
Consumer portfolio | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		28,859	29,526
Consumer portfolio | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		1,069	1,700
Consumer portfolio | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		147	210
Consumer portfolio | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio	[1]	125	81
Consumer portfolio | Residential mortgage
Credit quality of consumer loans
Loans categorized by LTV ratio		27,605	28,715
Consumer portfolio | Residential mortgage | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		26,622	27,162
Consumer portfolio | Residential mortgage | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		850	1,430
Consumer portfolio | Residential mortgage | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		60	92
Consumer portfolio | Residential mortgage | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio	[1]	73	31
Consumer portfolio | Home Equity loans
Credit quality of consumer loans
Loans categorized by LTV ratio		2,595	2,802
Consumer portfolio | Home Equity loans | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		2,237	2,364
Consumer portfolio | Home Equity loans | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		219	270
Consumer portfolio | Home Equity loans | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		87	118
Consumer portfolio | Home Equity loans | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio	[1]	52	50
Purchased credit-impaired loans | Consumer
Credit quality of consumer loans
Loans categorized by LTV ratio		157	195
Purchased credit-impaired loans | Consumer | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		112	131
Purchased credit-impaired loans | Consumer | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		34	45
Purchased credit-impaired loans | Consumer | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		10	18
Purchased credit-impaired loans | Consumer | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 1	$ 1

[1] Represents loans for which management was not able to obtain refreshed property values.