Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Held-to-maturity securities, fair value	$ 11,261,000,000	$ 11,565,000,000
Unearned income on loans	674,000,000	736,000,000
Loans held for sale	0	0
Aggregate amount of certificates of deposit, denominations	$ 100,000,000,000	$ 100,000,000,000
Common shares, par value (in usd per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	1,400,000,000	1,400,000,000
Common shares, shares issued (in shares)	1,256,702,081	1,256,702,081
Treasury stock, shares (in shares)	222,414,857	187,617,832
Residential Mortgage [Member]
Loans held for sale	$ 87,000,000	$ 71,000,000

Aggregate amount of certificates of deposit.

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Face amount or stated value per share of common stock.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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