Fair Value Measurements (Carrying Amounts and Estimated Fair Values for Certain Financial Instruments) (Detail) - USD ($) $ in Millions		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Financial assets:
Cash and due from banks		$ 2,392	[1]	$ 2,540	[1]	$ 3,091	$ 3,178
Held-to-maturity securities, amortized cost	[2]	26		70
Other short-term investments		2,754		2,671
Loans held for sale	[3]	751		903
Portfolio loans and leases, net		90,845		91,310
Other securities, fair value	[4]	31,183		29,044
Held-to-maturity securities, fair value		26		70
Loans held for sale		686		519
Portfolio loans and leases at fair value		143		167
Financial liabilities:
Deposits	[5]	103,821		103,205
Federal funds purchased		132		151
Other short-term borrowings		3,535		1,507
Long-term debt	[1]	14,388		15,810	[6]
Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		143		167
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks		2,392		2,540
Held-to-maturity securities, amortized cost		26		70
Other short-term investments		2,754		2,671
Loans held for sale		65		384
Portfolio loans and leases, net		90,702		91,143
Unallocated Allowance for Loan and Lease Losses		(112)		(115)
Financial liabilities:
Deposits		103,821		103,205
Federal funds purchased		132		151
Other short-term borrowings		3,535		1,507
Long-term debt		14,388		15,810	[7]
Carrying (Reported) Amount, Fair Value Disclosure | FHLB and FRB restricted stock holdings
Financial assets:
Other securities		607		604
Carrying (Reported) Amount, Fair Value Disclosure | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases, net		40,958		41,479
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases, net		6,817		6,840
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases, net		3,887		3,190
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases, net		3,959		3,807
Carrying (Reported) Amount, Fair Value Disclosure | Residential Mortgage
Financial assets:
Portfolio loans and leases, net		14,812		13,449
Carrying (Reported) Amount, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases, net		7,637		8,234
Carrying (Reported) Amount, Fair Value Disclosure | Automobile Loans
Financial assets:
Portfolio loans and leases, net		9,941		11,453
Carrying (Reported) Amount, Fair Value Disclosure | Credit Card
Financial assets:
Portfolio loans and leases, net		2,135		2,160
Carrying (Reported) Amount, Fair Value Disclosure | Other Consumer Loans and Leases
Financial assets:
Portfolio loans and leases, net		668		646
Total Fair Value
Financial assets:
Cash and due from banks, fair value		2,392		2,540
Held-to-maturity securities, fair value		26		70
Other short term investments, fair value		2,754		2,671
Portfolio loans and leases at fair value		92,872		92,282
Financial liabilities:
Deposits, fair value		103,811		103,219
Federal funds purchased, fair value		132		151
Other short-term borrowings, fair value		3,535		1,507
Long term debt, fair value		14,833		16,228	[7]
Total Fair Value | Non Fair Value Option HFS Loans
Financial assets:
Loans held for sale		65		384
Total Fair Value | FHLB and FRB restricted stock holdings
Financial assets:
Other securities, fair value		607		604
Total Fair Value | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		41,976		41,802
Total Fair Value | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		6,735		6,656
Total Fair Value | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,853		2,918
Total Fair Value | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,651		3,533
Total Fair Value | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		15,415		14,061
Total Fair Value | Home Equity
Financial assets:
Portfolio loans and leases at fair value		8,421		8,948
Total Fair Value | Automobile Loans
Financial assets:
Portfolio loans and leases at fair value		9,640		11,170
Total Fair Value | Credit Card
Financial assets:
Portfolio loans and leases at fair value		2,503		2,551
Total Fair Value | Other Consumer Loans and Leases
Financial assets:
Portfolio loans and leases at fair value		678		643
Total Fair Value | Fair Value, Inputs, Level 1
Financial assets:
Cash and due from banks, fair value		2,392		2,540
Other short term investments, fair value		2,754		2,671
Financial liabilities:
Federal funds purchased, fair value		132		151
Long term debt, fair value		14,288		15,603	[7]
Total Fair Value | Fair Value, Inputs, Level 2
Financial liabilities:
Deposits, fair value		103,811		103,219
Other short-term borrowings, fair value		3,535		1,507
Long term debt, fair value		545		625	[7]
Total Fair Value | Fair Value, Inputs, Level 2 | FHLB and FRB restricted stock holdings
Financial assets:
Other securities, fair value		607		604
Total Fair Value | Fair Value, Inputs, Level 3
Financial assets:
Held-to-maturity securities, fair value		26		70
Portfolio loans and leases at fair value		92,872		92,282
Total Fair Value | Fair Value, Inputs, Level 3 | Non Fair Value Option HFS Loans
Financial assets:
Loans held for sale		65		384
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		41,976		41,802
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		6,735		6,656
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,853		2,918
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,651		3,533
Total Fair Value | Fair Value, Inputs, Level 3 | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		15,415		14,061
Total Fair Value | Fair Value, Inputs, Level 3 | Home Equity
Financial assets:
Portfolio loans and leases at fair value		8,421		8,948
Total Fair Value | Fair Value, Inputs, Level 3 | Automobile Loans
Financial assets:
Portfolio loans and leases at fair value		9,640		11,170
Total Fair Value | Fair Value, Inputs, Level 3 | Credit Card
Financial assets:
Portfolio loans and leases at fair value		2,503		2,551
Total Fair Value | Fair Value, Inputs, Level 3 | Other Consumer Loans and Leases
Financial assets:
Portfolio loans and leases at fair value		$ 678		$ 643

[1] Includes $ 85 and $ 152 of cash and due from banks, $ 1,216 and $ 2,537 of portfolio loans and leases, $ (26) and $ (28) of ALLL, $ 9 and $ 14 of other assets, $ 3 and $ 3 of other liabilities and $ 1,094 and $ 2,487 of long-term debt from consolidated VIEs that are included in their respective captions above at December 31, 2016 and 2015 , respectively. For further information, refer to Note 11.

[2] Fair value of $ 26 and $ 70 at December 31, 2016 and 2015 , respectively.

[3] Includes $ 686 and $ 519 of residential mortgage loans held for sale measured at fair value at December 31, 2016 and 2015 , respectively.

[4] Amortized cost of $ 31,024 and $ 28,678 at December 31, 2016 and 2015 , respectively.

[5] Includes $ 0 and $ 628 of deposits held for sale at December 31, 2016 and 2015 , respectively.

[6] Upon adoption of ASU 2015-03 on January 1, 2016, the December 31, 2015 Consolidated Balance Sheet was adjusted to reflect the reclassification of $34 of debt issuance costs from other assets to long-term debt. For further inform ation refer to Note 1 .

[7] (a) Upon adoption of ASU 2015-03 on January 1, 2016, the December 31, 2015 Consolidated Balance Sheet was adjusted to reflect the re classification of $34 of debt issuance costs from other assets to long-term debt. For further information, refer to Note 1 .