Loans and Allowance for Loan Losses (Details 9) - USD ($) $ in Millions		6 Months Ended		12 Months Ended
		Jun. 30, 2016		Dec. 31, 2015
Consumer
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 30,617		$ 29,801
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		$ 29,420		$ 28,439
Percentage of total loans categorized by LTV ratio		96.00%		95.00%
Consumer | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 946		$ 1,053
Percentage of total loans categorized by LTV ratio		3.00%		4.00%
Consumer | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 121		$ 144
Percentage of total loans categorized by LTV ratio		0.00%		0.00%
Consumer | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 130		$ 165
Percentage of total loans categorized by LTV ratio		1.00%		1.00%
Consumer portfolio
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 30,492		$ 29,654
Consumer portfolio | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		29,326		28,333
Consumer portfolio | LTV Ratio Greater than 80 Percent and Less than 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		922		1,021
Consumer portfolio | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		115		135
Consumer portfolio | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio		129	[1]	165
Consumer portfolio | Residential mortgage
Credit quality of consumer loans
Loans categorized by LTV ratio				27,109
Consumer portfolio | Residential mortgage | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		27,171		26,143
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		706		804
Consumer portfolio | Residential mortgage | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		40		52
Consumer portfolio | Residential mortgage | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio	[1]	83		110
Consumer portfolio | Home Equity loans
Credit quality of consumer loans
Loans categorized by LTV ratio		2,492		2,545
Consumer portfolio | Home Equity loans | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		2,155		2,190
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		216		217
Consumer portfolio | Home Equity loans | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		75		83
Consumer portfolio | Home Equity loans | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio	[1]	46		55
Purchased credit-impaired loans | Consumer
Credit quality of consumer loans
Loans categorized by LTV ratio		125		147
Purchased credit-impaired loans | Consumer | LTV Ratio Less than or Equal to 80 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		94		106
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		24		32
Purchased credit-impaired loans | Consumer | LTV Ratio Greater than or Equal to 100 Percent
Credit quality of consumer loans
Loans categorized by LTV ratio		6		9
Purchased credit-impaired loans | Consumer | No LTV Available
Credit quality of consumer loans
Loans categorized by LTV ratio		$ 1		$ 0

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