Fair Value Measurements (Carrying Amounts and Estimated Fair Values for Certain Financial Instruments) (Detail) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016	[1]
Financial assets:
Cash and due from banks		$ 2,052	$ 2,514	$ 2,203	$ 2,392
Held-to-maturity securities, amortized cost	[2]	19	24
Other short-term investments	[1]	1,636	2,753
Loans and leases held for sale	[3]	783	492
Portfolio loans and leases, net		90,855	90,774
Other securities, fair value	[4]	31,961	31,751
Held-to-maturity securities, fair value		19	24
Financial liabilities:
Deposits		104,131	103,162
Federal funds purchased		597	174
Other short-term borrowings		1,763	4,012
Long-term debt	[1]	14,321	14,904
Commercial
Financial assets:
Loans held for sale		8	0
Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		162		$ 142
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets:
Cash and due from banks		2,052	2,514
Held-to-maturity securities, amortized cost		19	24
Other short-term investments		1,636	2,753
Loans and leases held for sale		117	93
Portfolio loans and leases, net		90,693	90,637
Unallocated Allowance For Loan And Lease Losses		(108)	(120)
Financial liabilities:
Deposits		104,131	103,162
Federal funds purchased		597	174
Other short-term borrowings		1,763	4,012
Long-term debt		14,321	14,904
Carrying (Reported) Amount, Fair Value Disclosure | FHLB, FRB and DTCC restricted stock holdings
Financial assets:
Other securities		614	612
Carrying (Reported) Amount, Fair Value Disclosure | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases, net		40,858	40,519
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases, net		6,560	6,539
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases, net		4,666	4,530
Carrying (Reported) Amount, Fair Value Disclosure | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases, net		3,765	4,054
Carrying (Reported) Amount, Fair Value Disclosure | Residential Mortgage
Financial assets:
Portfolio loans and leases, net		15,392	15,365
Carrying (Reported) Amount, Fair Value Disclosure | Home Equity
Financial assets:
Portfolio loans and leases, net		6,560	6,968
Carrying (Reported) Amount, Fair Value Disclosure | Automobile Loans
Financial assets:
Portfolio loans and leases, net		8,899	9,074
Carrying (Reported) Amount, Fair Value Disclosure | Credit Card
Financial assets:
Portfolio loans and leases, net		2,146	2,182
Carrying (Reported) Amount, Fair Value Disclosure | Other Consumer Loans
Financial assets:
Portfolio loans and leases, net		1,955	1,526
Total Fair Value
Financial assets:
Cash and due from banks, fair value		2,052	2,514
Held-to-maturity securities, fair value		19	24
Other short term investments, fair value		1,636	2,753
Portfolio loans and leases at fair value		92,213	92,948
Financial liabilities:
Deposits, fair value		104,064	103,123
Federal funds purchased, fair value		597	174
Other short-term borrowings, fair value		1,763	4,012
Long term debt, fair value		14,652	15,574
Total Fair Value | Non Fair Value Option HFS Loans
Financial assets:
Loans held for sale		117	93
Total Fair Value | FHLB, FRB and DTCC restricted stock holdings
Financial assets:
Other securities, fair value		614	612
Total Fair Value | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		41,825	41,718
Total Fair Value | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		6,493	6,490
Total Fair Value | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		4,710	4,560
Total Fair Value | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,355	3,705
Total Fair Value | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		15,697	15,996
Total Fair Value | Home Equity
Financial assets:
Portfolio loans and leases at fair value		6,936	7,410
Total Fair Value | Automobile Loans
Financial assets:
Portfolio loans and leases at fair value		8,632	8,832
Total Fair Value | Credit Card
Financial assets:
Portfolio loans and leases at fair value		2,518	2,616
Total Fair Value | Other Consumer Loans
Financial assets:
Portfolio loans and leases at fair value		2,047	1,621
Total Fair Value | Fair Value, Inputs, Level 1
Financial assets:
Cash and due from banks, fair value		2,052	2,514
Other short term investments, fair value		1,636	2,753
Financial liabilities:
Federal funds purchased, fair value		597	174
Long term debt, fair value		14,223	15,045
Total Fair Value | Fair Value, Inputs, Level 2
Financial liabilities:
Deposits, fair value		104,064	103,123
Other short-term borrowings, fair value		1,763	4,012
Long term debt, fair value		429	529
Total Fair Value | Fair Value, Inputs, Level 2 | FHLB, FRB and DTCC restricted stock holdings
Financial assets:
Other securities, fair value		614	612
Total Fair Value | Fair Value, Inputs, Level 3
Financial assets:
Held-to-maturity securities, fair value		19	24
Portfolio loans and leases at fair value		92,213	92,948
Total Fair Value | Fair Value, Inputs, Level 3 | Non Fair Value Option HFS Loans
Financial assets:
Loans held for sale		117	93
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial and Industrial Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		41,825	41,718
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Mortgage Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		6,493	6,490
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Construction Loans | Commercial
Financial assets:
Portfolio loans and leases at fair value		4,710	4,560
Total Fair Value | Fair Value, Inputs, Level 3 | Commercial Leases | Commercial
Financial assets:
Portfolio loans and leases at fair value		3,355	3,705
Total Fair Value | Fair Value, Inputs, Level 3 | Residential Mortgage
Financial assets:
Portfolio loans and leases at fair value		15,697	15,996
Total Fair Value | Fair Value, Inputs, Level 3 | Home Equity
Financial assets:
Portfolio loans and leases at fair value		6,936	7,410
Total Fair Value | Fair Value, Inputs, Level 3 | Automobile Loans
Financial assets:
Portfolio loans and leases at fair value		8,632	8,832
Total Fair Value | Fair Value, Inputs, Level 3 | Credit Card
Financial assets:
Portfolio loans and leases at fair value		2,518	2,616
Total Fair Value | Fair Value, Inputs, Level 3 | Other Consumer Loans
Financial assets:
Portfolio loans and leases at fair value		$ 2,047	$ 1,621

[1] Includes $ 47 and $ 62 of other short-term investments , $ 908 and $ 1,297 of portfolio loans and leases, $ (5) and $ (6) of ALLL, $ 5 and $ 7 of other assets, $ 2 and $ 2 of other liabilities, and $ 830 and $ 1,190 of long-term debt from consolidated VIEs that are included in their respe ctive captions above at June 30, 2018 and December 31, 2017 , respectively. For further information refer to Note 9 .

[2] Fair value of $ 19 and $ 24 at June 30, 2018 and December 31, 2017 , respectively.

[3] Includes $ 658 and $ 399 of residential mortgage loans held for sale measured at fair value and $ 8 and $ 0 of commercial loans held for sale measured at fair value at June 30, 2018 and December 31, 2017 , respectively.

[4] Amortized cost of $ 32,589 and $ 31,577 at June 30, 2018 and December 31, 2017 , respectively.