Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	$ 1,104	$ 839
Loans and Leases Receivable, Net Amount	117,847	117,800
Nonmarketable equity investments	833	1,046
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,104	839
Loans and Leases Receivable, Net Amount	117,847	117,800
Nonmarketable equity investments	833	1,046
Deposits	84,486	79,022
Short-term Debt	8,371	12,673
Long-term Debt	51,061	54,128
Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,063	789
Loans and Leases Receivable, Net Amount	119,420	118,750
Nonmarketable equity investments	854	1,067
Deposits	82,715	78,469
Short-term Debt	8,372	12,675
Long-term Debt	53,115	56,120
Portion at Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity investments	0	0
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	0	0
Portion at Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	1,063	789
Loans and Leases Receivable, Net Amount	0	0
Nonmarketable equity investments	795	1,012
Deposits	0	0
Short-term Debt	0	0
Long-term Debt	19,604	22,036
Portion at Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity securities	0	0
Loans and Leases Receivable, Net Amount	119,420	118,750
Nonmarketable equity investments	59	55
Deposits	82,715	78,469
Short-term Debt	8,372	12,675
Long-term Debt	$ 33,511	$ 34,084

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The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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