Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Millions		Sep. 30, 2017		Dec. 31, 2016
Assets:
Available-for-sale securities, fair value	[1]	$ 31,480		$ 31,183
Trading securities		850		410
Commercial loans held for sale measured at FV		651		686
Commercial
Assets:
Commercial loans held for sale measured at FV		5		0
Residential mortgage loans
Assets:
Loans measured at FV		140		143
Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,869	[2]	30,576	[3]
Trading securities		850		410
Residential mortgage loans held for sale		651		686
Loans measured at FV	[4]	140		143
Commercial loans held for sale measured at FV		5
Mortgage servicing rights	[5]	848
Derivative assets	[6]	735		1,057
Total assets		34,098		32,872
Liabilities:
Derivative liabilities	[7]	499		666
Short positions	[7]	28		21
Total liabilities		527		687
Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		529		748
Liabilities:
Derivative liabilities		157		265
Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		130		202
Liabilities:
Derivative liabilities		130		204
Equity Contract | Fair value, recurring
Liabilities:
Derivative liabilities		136		91
Commodity Contract | Fair value, recurring
Assets:
Derivative assets		76		107
Liabilities:
Derivative liabilities		76		106
U.S. Treasury and federal agencies
Assets:
Available-for-sale securities, fair value		69		549
U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		69		549
Trading securities		21		23
Obligations of states and political subdivisions
Assets:
Available-for-sale securities, fair value		45		45
Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		45		45
Trading securities		35		39
Agency mortgage-backed securities | Residential mortgage backed securities
Assets:
Available-for-sale securities, fair value		15,933	[8]	15,608	[9]
Agency mortgage-backed securities | Residential mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,933		15,608
Trading securities		402		8
Agency mortgage-backed securities | Commercial mortgage backed securities
Assets:
Available-for-sale securities, fair value		9,232		9,055
Agency mortgage-backed securities | Commercial mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		9,232		9,055
Non-agency mortgage-backed securities | Commercial mortgage backed securities
Assets:
Available-for-sale securities, fair value		3,358		3,112
Non-agency mortgage-backed securities | Commercial mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		3,358		3,112
Asset-backed securities and other debt securities
Assets:
Available-for-sale securities, fair value		2,143		2,116
Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		2,143		2,116
Trading securities		52		15
Equity securities
Assets:
Available-for-sale securities, fair value		700	[10]	698	[11]
Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		89	[2]	91	[3]
Trading securities		340		325
Fair Value, Inputs, Level 1 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		157	[2],[12]	561	[3],[13]
Trading securities		341	[12]	325	[13]
Derivative assets	[6]	25	[12]	42	[13]
Total assets		523	[12]	928	[13]
Liabilities:
Derivative liabilities	[7]	10	[12]	30	[13]
Short positions	[7]	20	[12]	17	[13]
Total liabilities		30	[12]	47	[13]
Fair Value, Inputs, Level 1 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		2	[12]	20	[13]
Liabilities:
Derivative liabilities		2	[12]	3	[13]
Fair Value, Inputs, Level 1 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		23	[12]	22	[13]
Liabilities:
Derivative liabilities		8	[12]	27	[13]
Fair Value, Inputs, Level 1 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		69	[12]	471	[13]
Trading securities	[12]	1
Fair Value, Inputs, Level 1 | Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		88	[2],[12]	90	[3],[13]
Trading securities		340	[12]	325	[13]
Fair Value, Inputs, Level 2 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,712	[2],[12]	30,015	[3],[13]
Trading securities		509	[12]	85	[13]
Residential mortgage loans held for sale		651	[12]	686	[13]
Commercial loans held for sale measured at FV	[12]	5
Derivative assets	[6]	697	[12]	1,002	[13]
Total assets		32,574	[12]	31,788	[13]
Liabilities:
Derivative liabilities	[7]	348	[12]	540	[13]
Short positions	[7]	8	[12]	4	[13]
Total liabilities		356	[12]	544	[13]
Fair Value, Inputs, Level 2 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		514	[12]	715	[13]
Liabilities:
Derivative liabilities		150	[12]	257	[13]
Fair Value, Inputs, Level 2 | Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		130	[12]	202	[13]
Liabilities:
Derivative liabilities		130	[12]	204	[13]
Fair Value, Inputs, Level 2 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		53	[12]	85	[13]
Liabilities:
Derivative liabilities		68	[12]	79	[13]
Fair Value, Inputs, Level 2 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		0	[12]	78	[13]
Trading securities		20	[12]	23	[13]
Fair Value, Inputs, Level 2 | Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		45	[12]	45	[13]
Trading securities		35	[12]	39	[13]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Residential mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,933	[12]	15,608	[13]
Trading securities		402	[12]	8	[13]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Commercial mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		9,232	[12]	9,055	[13]
Fair Value, Inputs, Level 2 | Non-agency mortgage-backed securities | Commercial mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		3,358	[12]	3,112	[13]
Fair Value, Inputs, Level 2 | Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		2,143	[12]	2,116	[13]
Trading securities		52	[12]	15	[13]
Fair Value, Inputs, Level 2 | Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1	[2],[12]	1	[3],[13]
Fair Value, Inputs, Level 3 | Fair value, recurring
Assets:
Loans measured at FV	[4]	140		143
Mortgage servicing rights	[5]	848
Derivative assets	[6]	13		13
Total assets		1,001		156
Liabilities:
Derivative liabilities	[7]	141		96
Total liabilities		141		96
Fair Value, Inputs, Level 3 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		13		13
Liabilities:
Derivative liabilities		5		5
Fair Value, Inputs, Level 3 | Equity Contract | Fair value, recurring
Liabilities:
Derivative liabilities		$ 136		$ 91

[1] Amortized cost of $ 31,114 and $ 31,024 at September 30, 2017 and December 31, 2016 , respectively.

[2] Excludes FHLB, FRB and DTCC restricted stock holdings totaling $ 248 , $ 361 and $ 2 , respectively, at September 30, 2017 .

[3] Excludes FHLB, FRB , and DTCC restricted stock holdings totaling $ 248 , $ 358 and $ 1 , respectively, at December 31, 2016 .

[4] Includes residential mortgage loans originated as held for sale and subsequently transferred to held for investment.

[5] Effective January 1, 2017, the Bancorp has elected the fair value measurement method for all existing classes of its residential mortgage servicing rights. The servicing rights were measured at fair value at September 30, 2017 and were measured under the amortization method at December 31, 2016.

[6] Included in other assets in the Condensed Consolidated Balance Sheets.

[7] Included in other liabilities in the Condensed Consolidated Balance Sheets.

[8] Includes interest-only mortgage-backed securities of $ 36 as of September 30, 2017 , recorded at fair value with fair value changes recorded in securities gains, net, in the Condensed Consolidated Statements of Income.

[9] Includes interest-only mortgage-backed securities of $ 60 as of December 31, 2016 , recorded at fair value with fair value changes recorded in securities gains, net, in the Condensed Consolidated Statements of Income.

[10] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 361 and $ 2 , respectively, at September 30, 2017 , that are carried at cost, and certain mutual fund and equity security holdings.

[11] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 358 and $ 1 , respectively, at December 31, 2016 , that are carried at cost, and certain mutual fund and equity security holdings

[12] During both the three and nine months ended September 30, 2017 , no assets or liabilities were transferred between Level 1 and Level 2.

[13] During the year ended December 31, 2016 , no assets or liabilities were transferred between Level 1 and Level 2.