Fair Value Measurements - Nonrecurring Fair Value Inputs (Details) (USD $) In Millions, unless otherwise specified																9 Months Ended		12 Months Ended		9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended				9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Sep. 30, 2013 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]		Sep. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]		Dec. 31, 2012 Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Private Equity Investments and Funds [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Private Equity Investments and Funds [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow Market Comparables [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Residential Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Discounted Cash Flow [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Discounted Cash Flow [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Minimum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Sep. 30, 2013 Discounted Cash Flow [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]	Sep. 30, 2013 Discounted Cash Flow [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Discounted Cash Flow [Member] Loans and Securities [Member] Maximum [Member] Instruments Backed by Commercial Real Estate Assets [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans and Securities Fair Value Disclosure																$ 3,331	[1]	$ 4,478	[2]	$ 5,114	$ 9,932									$ 1,910	[2]	$ 388
Fair Value Inputs Yield, Weighted Average																7.00%		6.00%			3.00%											6.00%
Loans Held-for-sale, Fair Value Disclosure	8,217	11,659	8,217	11,659	913	[3],[4]	2,733	[3],[4]	274		1,006					609	[1]	2,733	[2]		748											388
Fair Value Inputs, Prepayment Rate, Weighted Average																9.00%		10.00%			15.00%
Loans and leases			10,196	9,002	3,016		2,287		5,114	[5]	8,576	[5]				2,366	[1]	1,286	[2]	5,114	9,184
Fair Value Inputs, Probability of Default, Weighted Average																7.00%		6.00%			7.00%
Fair Value Inputs, Loss Severity, Weighted Average																37.00%		43.00%			48.00%									88.00%		53.00%
Fair Value Inputs, Discount Rate, Weighted Average																				9.00%	15.00%
Fair Value Inputs, Yield																						2.00%	2.00%	3.00%	3.00%	25.00%	25.00%	6.00%	5.00%				5.00%	5.00%	13.00%	4.00%	18.00%	5.00%	14.00%	13.00%
Fair Value Inputs, Prepayment Rate																						1.00%	1.00%	3.00%	3.00%	35.00%	30.00%	20.00%	30.00%
Fair Value Inputs, Probability of Default																						0.00%	0.00%	0.00%	0.00%	20.00%	44.00%	28.00%	55.00%
Fair Value Inputs, Loss Severity																						0.00%	6.00%	8.00%	6.00%	85.00%	85.00%	61.00%	66.00%				73.00%	51.00%	18.00%	24.00%	83.00%	100.00%	82.00%	88.00%
Fair Value Inputs, Discount Rate																								0.00%	0.00%			19.00%	28.00%
Fair Value Inputs, Cost to Sell																				8.00%	8.00%
Other Assets, Fair Value Disclosure	$ 18,204	$ 26,490	$ 18,204	$ 26,490	$ 1,878		$ 3,129		$ 10		$ 111		$ 1,900	$ 934	$ 1,200															$ 1,910	[2]

[1] The categories are aggregated based upon product type which differs from financial statement classification. The following is a reconciliation to the line items in the table on page 237: Trading account assets – Corporate securities, trading loans and other of $3.8 billion, Trading account assets – Mortgage trading loans and ABS of $4.5 billion, AFS debt securities – Other taxable securities of $4.0 billion, AFS debt securities – Tax-exempt securities of $817 million, Loans and leases of $3.0 billion and LHFS of $913 million.

[2] The categories are aggregated based upon product type which differs from financial statement classification. The following is a reconciliation to the line items in the table on page 238: Trading account assets – Corporate securities, trading loans and other of $3.7 billion, Trading account assets – Mortgage trading loans and ABS of $4.9 billion, AFS debt securities – Other taxable securities of $3.9 billion, AFS debt securities – Tax-exempt securities of $1.1 billion, Loans and leases of $2.3 billion, LHFS of $2.7 billion and Other assets of $1.9 billion.

[3] Assets (liabilities). For assets, increase / (decrease) to Level 3 and for liabilities, (increase) / decrease to Level 3.

[4] Net derivatives include derivative assets of $10.0 billion and derivative liabilities of $7.0 billion.

[5] Losses represent charge-offs on real estate-secured loans