Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Millions		Dec. 31, 2016		Dec. 31, 2015
Assets:
Available-for-sale securities, fair value	[1]	$ 31,183		$ 29,044
Trading securities		410		386
Residential mortgage loans measured at fair value		143		167
Derivative assets		1,057		1,852
Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,576	[2]	28,440	[3]
Trading securities		410		386
Residential mortgage loans held for sale		686		519
Residential mortgage loans measured at fair value		143	[4]	167	[5]
Derivative assets		1,057	[6]	1,852	[7]
Total assets		32,872		31,364
Liabilities:
Derivative liabilities		666	[8]	938	[9]
Short positions		21	[8]	29	[9]
Total liabilities		687		967
Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		748		910
Liabilities:
Derivative liabilities		265		261
Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		202		386
Liabilities:
Derivative liabilities		204		340
Equity Contract | Fair value, recurring
Assets:
Derivative assets		0		262
Liabilities:
Derivative liabilities		91		61
Commodity Contract | Fair value, recurring
Assets:
Derivative assets		107		294
Liabilities:
Derivative liabilities		106		276
U.S. Treasury and federal agencies
Assets:
Available-for-sale securities, fair value		549		1,187
U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		549		1,187
Trading securities		23		19
Obligations of states and political subdivisions
Assets:
Available-for-sale securities, fair value		45		52
Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		45		52
Trading securities		39		9
Agency mortgage-backed securities | Residential mortgage-backed securities
Assets:
Available-for-sale securities, fair value	[10]	15,608		15,081
Agency mortgage-backed securities | Residential mortgage-backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,608		15,081
Trading securities		8		6
Agency mortgage-backed securities | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value		9,055		7,862
Agency mortgage-backed securities | Commercial mortgage-backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		9,055		7,862
Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Assets:
Available-for-sale securities, fair value		3,112		2,804
Non-agency mortgage-backed securities | Commercial mortgage-backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		3,112		2,804
Asset-backed securities and other debt securities
Assets:
Available-for-sale securities, fair value		2,116		1,355
Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		2,116		1,355
Trading securities		15		19
Equity securities
Assets:
Available-for-sale securities, fair value	[11]	698		703
Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		91	[2]	99	[3]
Trading securities		325		333
Fair Value, Inputs, Level 1 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		561	[2],[12]	198	[3],[13]
Trading securities		325	[12]	333	[13]
Derivative assets		42	[6],[12]	57	[7],[13]
Total assets		928	[12]	588	[13]
Liabilities:
Derivative liabilities		30	[8],[12]	38	[9],[13]
Short positions		17	[8],[12]	22	[9],[13]
Total liabilities		47	[12]	60	[13]
Fair Value, Inputs, Level 1 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		20	[12]	3	[13]
Liabilities:
Derivative liabilities		3	[12]	1	[13]
Fair Value, Inputs, Level 1 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		22	[12]	54	[13]
Liabilities:
Derivative liabilities		27	[12]	37	[13]
Fair Value, Inputs, Level 1 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		471	[12]	100	[13]
Fair Value, Inputs, Level 1 | Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		90	[2],[12]	98	[3],[13]
Trading securities		325	[12]	333	[13]
Fair Value, Inputs, Level 2 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,015	[2],[12]	28,242	[3],[13]
Trading securities		85	[12]	53	[13]
Residential mortgage loans measured at fair value		686	[12]	519	[13]
Derivative assets		1,002	[6],[12]	1,518	[7],[13]
Total assets		31,788	[12]	30,332	[13]
Liabilities:
Derivative liabilities		540	[8],[12]	836	[9],[13]
Short positions		4	[8],[12]	7	[9],[13]
Total liabilities		544	[12]	843	[13]
Fair Value, Inputs, Level 2 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		715	[12]	892	[13]
Liabilities:
Derivative liabilities		257	[12]	257	[13]
Fair Value, Inputs, Level 2 | Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		202	[12]	386	[13]
Liabilities:
Derivative liabilities		204	[12]	340	[13]
Fair Value, Inputs, Level 2 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		85	[12]	240	[13]
Liabilities:
Derivative liabilities		79	[12]	239	[13]
Fair Value, Inputs, Level 2 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		78	[12]	1,087	[13]
Trading securities		23	[12]	19	[13]
Fair Value, Inputs, Level 2 | Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		45	[12]	52	[13]
Trading securities		39	[12]	9	[13]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Residential mortgage-backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,608	[12]	15,081	[13]
Trading securities		8	[12]	6	[13]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Commercial mortgage-backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		9,055	[12]	7,862	[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		3,112	[12]	2,804	[13]
Fair Value, Inputs, Level 2 | Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		2,116	[12]	1,355	[13]
Trading securities		15	[12]	19	[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:
Residential mortgage loans measured at fair value		143	[4]	167	[5]
Derivative assets		13	[6]	277	[7]
Total assets		156		444
Liabilities:
Derivative liabilities		96	[8]	64	[9]
Total liabilities		96		64
Fair Value, Inputs, Level 3 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		13		15
Liabilities:
Derivative liabilities		5		3
Fair Value, Inputs, Level 3 | Equity Contract | Fair value, recurring
Assets:
Derivative assets		0		262
Liabilities:
Derivative liabilities		$ 91		$ 61

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

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

[3] Excludes FHLB, FRB and DTCC restricted stock totaling $ 248 , $ 355 and $1 , respectively, at December 31, 2015 .

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

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

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

[7] Included in other assets in the Consolidated Balance Sheets.

[8] Included in other liabilities in the Consolidated Balance Sheets.

[9] Included in other liabilities in the Consolidated Balance Sheet s.

[10] Includes interest-only mortgage-backed securities of $ 60 and $ 50 as of December 31, 2016 and 2015 , respectively, recorded at fair value with fair value changes recorded in securities gains, net , i n the Consolidated Statements of Income .

[11] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 358 , and $ 1 , respectively, at December 31, 2016 and $ 248 , $ 355 and $ 1 , respectively, at December 31, 2015 , that are carried at cost, and certain mutual fund and equity security holdings.

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

[13] During the year ended December 31, 2015 , no assets or liabilities were transferred between Level 1 and Level 2.