Fair Value Measurements (Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Millions		Jun. 30, 2016		Dec. 31, 2015
Assets:
Available-for-sale securities, fair value	[1]	$ 31,455		$ 29,044
Trading securities		401		386
Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,850	[2]	28,440	[3]
Trading securities		401		386
Residential mortgage loans held for sale		852		519
Residential mortgage loans measured at FV	[4]	154		167
Derivative assets	[5]	2,179		1,852
Total assets		34,436		31,364
Liabilities:
Derivative liabilities	[6]	979		938
Short positions	[6]	20		29
Total liabilities		999		967
Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		1,436		910
Liabilities:
Derivative liabilities		504		261
Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		279		386
Liabilities:
Derivative liabilities		253		340
Equity Contract | Fair value, recurring
Assets:
Derivative assets		327		262
Liabilities:
Derivative liabilities		99		61
Commodity Contract | Fair value, recurring
Assets:
Derivative assets		137		294
Liabilities:
Derivative liabilities		123		276
U.S. Treasury and federal agencies
Assets:
Available-for-sale securities, fair value		1,155		1,187
U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1,155		1,187
Trading securities		16		19
Obligations of states and political subdivisions
Assets:
Available-for-sale securities, fair value		52		52
Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		52		52
Trading securities		96		9
Agency mortgage-backed securities | Residential mortgage backed securities
Assets:
Available-for-sale securities, fair value		15,694	[7]	15,081	[8]
Agency mortgage-backed securities | Residential mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,694		15,081
Trading securities		8		6
Agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member]
Assets:
Available-for-sale securities, fair value		8,926		7,862
Agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member] | Fair value, recurring
Assets:
Available-for-sale securities, fair value		8,926		7,862
Non-agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member]
Assets:
Available-for-sale securities, fair value		3,079		2,804
Non-agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member] | Fair value, recurring
Assets:
Available-for-sale securities, fair value		3,079		2,804
Asset-backed securities and other debt securities
Assets:
Available-for-sale securities, fair value		1,849		1,355
Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1,849		1,355
Trading securities		17		19
Equity securities
Assets:
Available-for-sale securities, fair value		700	[9]	703	[10]
Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		95	[2]	99	[3]
Trading securities		264		333
Fair Value, Inputs, Level 1 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		172	[2],[11]	198	[3],[12]
Trading securities		264	[11]	333	[12]
Derivative assets	[5]	21	[11]	57	[12]
Total assets		457	[11]	588	[12]
Liabilities:
Derivative liabilities	[6]	35	[11]	38	[12]
Short positions	[6]	14	[11]	22	[12]
Total liabilities		49	[11]	60	[12]
Fair Value, Inputs, Level 1 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets	[12]			3
Liabilities:
Derivative liabilities		17	[11]	1	[12]
Fair Value, Inputs, Level 1 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		21	[11]	54	[12]
Liabilities:
Derivative liabilities		18	[11]	37	[12]
Fair Value, Inputs, Level 1 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		78	[11]	100	[12]
Fair Value, Inputs, Level 1 | Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		94	[2],[11]	98	[3],[12]
Trading securities		264	[11]	333	[12]
Fair Value, Inputs, Level 2 | Fair value, recurring
Assets:
Available-for-sale securities, fair value		30,678	[2],[11]	28,242	[3],[12]
Trading securities		137	[11]	53	[12]
Residential mortgage loans held for sale		852	[11]	519	[12]
Derivative assets	[5]	1,797	[11]	1,518	[12]
Total assets		33,464	[11]	30,332	[12]
Liabilities:
Derivative liabilities	[6]	841	[11]	836	[12]
Short positions	[6]	6	[11]	7	[12]
Total liabilities		847	[11]	843	[12]
Fair Value, Inputs, Level 2 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		1,402	[11]	892	[12]
Liabilities:
Derivative liabilities		483	[11]	257	[12]
Fair Value, Inputs, Level 2 | Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets		279	[11]	386	[12]
Liabilities:
Derivative liabilities		253	[11]	340	[12]
Fair Value, Inputs, Level 2 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets		116	[11]	240	[12]
Liabilities:
Derivative liabilities		105	[11]	239	[12]
Fair Value, Inputs, Level 2 | U.S. Treasury and federal agencies | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1,077	[11]	1,087	[12]
Trading securities		16	[11]	19	[12]
Fair Value, Inputs, Level 2 | Obligations of states and political subdivisions | Fair value, recurring
Assets:
Available-for-sale securities, fair value		52	[11]	52	[12]
Trading securities		96	[11]	9	[12]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Residential mortgage backed securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		15,694	[11]	15,081	[12]
Trading securities		8	[11]	6	[12]
Fair Value, Inputs, Level 2 | Agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member] | Fair value, recurring
Assets:
Available-for-sale securities, fair value		8,926	[11]	7,862	[12]
Fair Value, Inputs, Level 2 | Non-agency mortgage-backed securities | Commercial Mortgage Backed Securities [Member] | Fair value, recurring
Assets:
Available-for-sale securities, fair value		3,079	[11]	2,804	[12]
Fair Value, Inputs, Level 2 | Asset-backed securities and other debt securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1,849	[11]	1,355	[12]
Trading securities		17	[11]	19	[12]
Fair Value, Inputs, Level 2 | Equity securities | Fair value, recurring
Assets:
Available-for-sale securities, fair value		1	[2],[11]	1	[3],[12]
Fair Value, Inputs, Level 3 | Fair value, recurring
Assets:
Residential mortgage loans measured at FV		154		167	[4]
Derivative assets	[5]	361		277
Total assets		515		444
Liabilities:
Derivative liabilities	[6]	103		64
Total liabilities		103		64
Fair Value, Inputs, Level 3 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets		34		15
Liabilities:
Derivative liabilities		4		3
Fair Value, Inputs, Level 3 | Equity Contract | Fair value, recurring
Assets:
Derivative assets		327		262
Liabilities:
Derivative liabilities		$ 99		$ 61

[1] Amortized cost of $ 30,101 and $ 28,678 at June 30, 2016 and Dec ember 31, 2015 , respectively.

[2] Excludes FHLB, FRB and DTCC restricted stock holdings totaling $ 248 , $ 356 and $ 1 , respectively, at June 30, 2016 .

[3] Excludes FHLB and FRB 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] Included in other assets in the Condensed Consolidated Balance Sheets .

[6] Included in other liabilities in the Condensed Consolidat ed Balance Sheets .

[7] Includes interest-only mortgage- backed securities of $ 36 as of June 30, 2016 recorded at fair value with fair value changes re corded in securities gains, net , in the Condensed Consolidated Statement s of Income.

[8] Includes interest-only mortgage- backed securities of $ 50 as of December 31, 2015 , recorded at fair value with fair value changes re corded in securities gains, net , in the Condensed Consolidated Statement s of Income.

[9] Equity securities consist of FHLB, FRB and DTCC restricted stock holdings of $ 248 , $ 356 and $ 1 , respectively , at June 30, 2016 , that are carried at cost, and certain mutual fund and equity security holdings.

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

[11] During both the three and six months ended June 30, 2016 , no assets or liabilities were transferred between Level 1 and Level 2.

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