Fair Value Election and Measurement Level 3 Significant Unobservable Input Assumptions (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
level 3 fair value assumptions [Line Items]
Trading Securities	[1]	$ 5,093		$ 6,067
Available-for-sale Securities	[2]	31,416		30,672
Loans Held-for-sale, Fair Value Disclosure		1,577		3,540
Loans Receivable, Fair Value Disclosure		196		222
Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Trading Securities	[3]	16		28
Available-for-sale Securities	[3]	490		633
Loans Held-for-sale, Fair Value Disclosure	[4]	54		17
Fair Value, Measurements, Recurring [Member]
level 3 fair value assumptions [Line Items]
Trading Securities		5,093		6,067
Available-for-sale Securities		31,416		30,672
Loans Held-for-sale, Fair Value Disclosure		1,577		3,540
Loans Receivable, Fair Value Disclosure		196		222
Servicing Asset at Fair Value, Amount		1,710		1,572
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Trading Securities		16		28
Available-for-sale Securities		490		633
Loans Held-for-sale, Fair Value Disclosure		0		12
Loans Receivable, Fair Value Disclosure		196		222
Servicing Asset at Fair Value, Amount		1,710		1,572
Fair Value, Measurements, Recurring [Member] | Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Other Assets, Fair Value Disclosure		0	[5]	6	[6]
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member] | Cost Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Available-for-sale Securities		418		540
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Available-for-sale Securities		8		10
Fair Value, Measurements, Recurring [Member] | Other Debt Obligations [Member] | Cost Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Available-for-sale Securities		5		5
Fair Value, Measurements, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Cost Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Available-for-sale Securities				4
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member] | Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Available-for-sale Securities		59		74
Fair Value, Measurements, Recurring [Member] | Residential Mortgage, Loans Held For Sale [Member] | Income Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Loans Held-for-sale, Fair Value Disclosure				$ 12
Fair Value, Measurements, Recurring [Member] | Residential Mortgage, Loans Held For Sale [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread				(1.04%)
Fair Value Inputs, Prepayment Rate				2.00%
Fair Value Inputs, Probability of Default				0.00%
Fair Value, Measurements, Recurring [Member] | Residential Mortgage, Loans Held For Sale [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread				(1.25%)
Fair Value Inputs, Prepayment Rate				28.00%
Fair Value Inputs, Probability of Default				3.00%
Fair Value, Measurements, Recurring [Member] | Residential Mortgage, Loans Held For Sale [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread				(1.24%)
Fair Value Inputs, Prepayment Rate				7.00%
Fair Value Inputs, Probability of Default				0.40%
Fair Value, Measurements, Recurring [Member] | Loans Held For Investment [Member] | Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Loans Receivable, Fair Value Disclosure		4		$ 3
Fair Value, Measurements, Recurring [Member] | Loans Held For Investment [Member] | Income Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Loans Receivable, Fair Value Disclosure		$ 192		$ 219
Fair Value, Measurements, Recurring [Member] | Loans Held For Investment [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(0.62%)		(0.62%)
Fair Value Inputs, Prepayment Rate		2.00%		3.00%
Fair Value Inputs, Probability of Default		0.00%		0.00%
Fair Value, Measurements, Recurring [Member] | Loans Held For Investment [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(7.84%)		(7.84%)
Fair Value Inputs, Prepayment Rate		34.00%		36.00%
Fair Value Inputs, Probability of Default		5.00%		5.00%
Fair Value, Measurements, Recurring [Member] | Loans Held For Investment [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(2.15%)		(1.84%)
Fair Value Inputs, Prepayment Rate		11.00%		13.00%
Fair Value Inputs, Probability of Default		0.70%		2.10%
Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Rights [Member] | Income Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Servicing Asset at Fair Value, Amount		$ 1,710		$ 1,572
Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Rights [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(1.00%)		(0.00%)
Fair Value Inputs, Prepayment Rate		6.00%		1.00%
Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Rights [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(125.00%)		(122.00%)
Fair Value Inputs, Prepayment Rate		30.00%		25.00%
Fair Value, Measurements, Recurring [Member] | Mortgage Servicing Rights [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Option Adjusted Spread		(4.00%)		(8.00%)
Fair Value Inputs, Prepayment Rate		13.00%		9.00%
Fair Value, Measurements, Recurring [Member] | Other Assets [Member] | Market Approach Valuation Technique [Member] | Minimum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Pull Through Rate		41.00%		40.00%
Fair Value Inputs, Msr Value		0.41%		0.22%
Fair Value, Measurements, Recurring [Member] | Other Assets [Member] | Market Approach Valuation Technique [Member] | Maximum [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Pull Through Rate		100.00%		100.00%
Fair Value Inputs, Msr Value		1.90%		1.70%
Fair Value, Measurements, Recurring [Member] | Other Assets [Member] | Market Approach Valuation Technique [Member] | Weighted Average [Member] | Fair Value, Inputs, Level 3 [Member]
level 3 fair value assumptions [Line Items]
Fair Value Inputs, Pull Through Rate		81.00%		81.00%
Fair Value Inputs, Msr Value		1.13%		1.06%

[1] Includes trading securities pledged as collateral where counterparties have the right to sell or repledge the collateral of $1,086 million and $1,437 million at December 31, 2017 and December 31, 2016, respectively.

[2] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $223 million and $0 million at December 31, 2017 and December 31, 2016, respectively.

[3] Trading assets and derivative instruments, securities AFS, and trading liabilities and derivative instruments that are classified as level 1 are valued based on quoted prices observed in active markets. For those instruments classified as level 2 or 3, refer to the respective valuation discussions within this footnote.

[4] LHFS are generally valued based on observable current market prices or, if quoted market prices are not available, quoted market prices of similar instruments. Refer to the LHFS section within this footnote for further discussion. When valuation assumptions are not readily observable in the market, instruments are valued based on the best available data to approximate fair value. This data may be internally developed and considers risk premiums that a market participant would require under then-current market conditions.

[5] Amount represents the net of IRLC assets and liabilities and includes the derivative liability associated with the Company's sale of Visa shares. Refer to the "Trading Liabilities and Derivative Instruments" section herein for a discussion of valuation assumptions related to the Visa derivative liability.

[6] Amount represents the net of IRLC assets and liabilities and includes the derivative liability associated with the Company's sale of Visa shares. Refer to the "Trading Liabilities and Derivative Instruments" section herein for a discussion of valuation assumptions related to the Visa derivative liability.