Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) - Level 3 [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance		$ 3,356	$ 3,328
Fair Value Assets, Gains (Losses) Included In Earnings		133	65
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income		0	0
Fair Value Assets, Purchases		0	14
Fair Value Assets, Issuances		(35)	0
Fair Value Assets, Settlements		(1,252)	(65)
Fair Value Assets, Transfers Into Level 3		4	106
Fair Value Assets, Transfers Out of Level 3		1	(92)
Fair Value Assets, Ending Balance		2,207	3,356
Fair Value Assets, Current Period Unrealized Gains (Losses)		85	41
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance		(1,906)	(2,613)
Fair Value Liability, Gains (Losses) Included In Earnings		(133)	(116)
Fair Value, Liability, Gains (Losses) Included in Other Comprehensive Income		0	0
Fair Value Liability, Purchases		0	0
Fair Value Liability, Issuances		(499)	(501)
Fair Value Liability, Settlements		681	926
Fair Value Liability, Transfers Into Level 3		(43)	(55)
Fair Value Liability, Transfers Out of Level 3		362	453
Fair Value Liability, Ending Balance		(1,538)	(1,906)
Fair Value Liability, Current Period Unrealized Gains (Losses)		(99)	(73)
Interest rate contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[1]	1	1
Fair Value Assets, Gains (Losses) Included In Earnings	[1]	(1)	0
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[1]	0	0
Fair Value Assets, Purchases	[1]	0	0
Fair Value Assets, Issuances	[1]	0	0
Fair Value Assets, Settlements	[1]	0	0
Fair Value Assets, Transfers Into Level 3	[1]	0	0
Fair Value Assets, Transfers Out of Level 3	[1]	0	0
Fair Value Assets, Ending Balance	[1]	0	1
Fair Value Assets, Current Period Unrealized Gains (Losses)	[1]	(1)	0
Foreign exchange contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[1]	0	0
Fair Value Assets, Gains (Losses) Included In Earnings	[1]	0	0
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[1]	0	0
Fair Value Assets, Purchases	[1]	0	0
Fair Value Assets, Issuances	[1]	0	0
Fair Value Assets, Settlements	[1]	0	0
Fair Value Assets, Transfers Into Level 3	[1]	0	0
Fair Value Assets, Transfers Out of Level 3	[1]	0	0
Fair Value Assets, Ending Balance	[1]	0	0
Fair Value Assets, Current Period Unrealized Gains (Losses)	[1]	0	0
Equity contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[1]	(2)	(83)
Fair Value Assets, Gains (Losses) Included In Earnings	[1]	102	63
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[1]	0	0
Fair Value Assets, Purchases	[1]	0	0
Fair Value Assets, Issuances	[1]	0	0
Fair Value Assets, Settlements	[1]	(24)	13
Fair Value Assets, Transfers Into Level 3	[1]	4	1
Fair Value Assets, Transfers Out of Level 3	[1]	1	4
Fair Value Assets, Ending Balance	[1]	81	(2)
Fair Value Assets, Current Period Unrealized Gains (Losses)	[1]	68	37
Credit contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[1]	193	179
Fair Value Assets, Gains (Losses) Included In Earnings	[1]	(7)	16
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[1]	0	0
Fair Value Assets, Purchases	[1]	0	0
Fair Value Assets, Issuances	[1]	0	0
Fair Value Assets, Settlements	[1]	(72)	(2)
Fair Value Assets, Transfers Into Level 3	[1]	0	0
Fair Value Assets, Transfers Out of Level 3	[1]	0	0
Fair Value Assets, Ending Balance	[1]	114	193
Fair Value Assets, Current Period Unrealized Gains (Losses)	[1]	(16)	4
Other Contract [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[1],[2]	(9)	0
Fair Value Assets, Gains (Losses) Included In Earnings	[1],[2]	(10)	0
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[1],[2]	0	0
Fair Value Assets, Purchases	[1],[2]	0	0
Fair Value Assets, Issuances	[1],[2]	(35)	0
Fair Value Assets, Settlements	[1],[2]	8	(9)
Fair Value Assets, Transfers Into Level 3	[1],[2]	0	0
Fair Value Assets, Transfers Out of Level 3	[1],[2]	0	0
Fair Value Assets, Ending Balance	[1],[2]	(46)	(9)
Fair Value Assets, Current Period Unrealized Gains (Losses)	[1],[2]	0	0
Collateralized debt obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[3]	184	221
Fair Value Assets, Gains (Losses) Included In Earnings	[3]	28	13
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[3]	0	0
Fair Value Assets, Purchases	[3]	0	0
Fair Value Assets, Issuances	[3]	0	0
Fair Value Assets, Settlements	[3]	(83)	(50)
Fair Value Assets, Transfers Into Level 3	[3]	0	0
Fair Value Assets, Transfers Out of Level 3	[3]	0	0
Fair Value Assets, Ending Balance	[3]	129	184
Fair Value Assets, Current Period Unrealized Gains (Losses)	[3]	13	0
Corporate and other domestic debt securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[3]	2,884	2,870
Fair Value Assets, Gains (Losses) Included In Earnings	[3]	0	0
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[3]	0	0
Fair Value Assets, Purchases	[3]	0	14
Fair Value Assets, Issuances	[3]	0	0
Fair Value Assets, Settlements	[3]	(1,081)	0
Fair Value Assets, Transfers Into Level 3	[3]	0	0
Fair Value Assets, Transfers Out of Level 3	[3]	0	0
Fair Value Assets, Ending Balance	[3]	1,803	2,884
Fair Value Assets, Current Period Unrealized Gains (Losses)	[3]	0	0
Other asset-backed securities available-for-sale [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[4]	105	0
Fair Value Assets, Gains (Losses) Included In Earnings	[4]	6	0
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[4]	0	0
Fair Value Assets, Purchases	[4]	0	0
Fair Value Assets, Issuances	[4]	0	0
Fair Value Assets, Settlements	[4]	0	0
Fair Value Assets, Transfers Into Level 3	[4]	0	105
Fair Value Assets, Transfers Out of Level 3	[4]	0	0
Fair Value Assets, Ending Balance	[4]	111	105
Fair Value Assets, Current Period Unrealized Gains (Losses)	[4]	6	0
Mortgage servicing rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[5]	0	140
Fair Value Assets, Gains (Losses) Included In Earnings	[5]		(27)
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[5]		0
Fair Value Assets, Purchases	[5]		0
Fair Value Assets, Issuances	[5]		0
Fair Value Assets, Settlements	[5]		(17)
Fair Value Assets, Transfers Into Level 3	[5]		0
Fair Value Assets, Transfers Out of Level 3	[5]		(96)
Fair Value Assets, Ending Balance	[5]		0
Fair Value Assets, Current Period Unrealized Gains (Losses)	[5]		0
Domestic Deposits [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	[6]	(1,407)	(1,867)
Fair Value Liability, Gains (Losses) Included In Earnings	[6]	(48)	(82)
Fair Value, Liability, Gains (Losses) Included in Other Comprehensive Income	[6]	7	0
Fair Value Liability, Purchases	[6]	0	0
Fair Value Liability, Issuances	[6]	(204)	(238)
Fair Value Liability, Settlements	[6]	526	623
Fair Value Liability, Transfers Into Level 3	[6]	(31)	(55)
Fair Value Liability, Transfers Out of Level 3	[6]	260	212
Fair Value Liability, Ending Balance	[6]	(897)	(1,407)
Fair Value Liability, Current Period Unrealized Gains (Losses)	[6]	(28)	(44)
Long-term debt [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Liability, Beginning Balance	[6]	(499)	(746)
Fair Value Liability, Gains (Losses) Included In Earnings	[6]	(85)	(34)
Fair Value, Liability, Gains (Losses) Included in Other Comprehensive Income	[6]	(7)	0
Fair Value Liability, Purchases	[6]	0	0
Fair Value Liability, Issuances	[6]	(295)	(263)
Fair Value Liability, Settlements	[6]	155	303
Fair Value Liability, Transfers Into Level 3	[6]	(12)	0
Fair Value Liability, Transfers Out of Level 3	[6]	102	241
Fair Value Liability, Ending Balance	[6]	(641)	(499)
Fair Value Liability, Current Period Unrealized Gains (Losses)	[6]	(71)	(29)
Other assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value Assets, Beginning Balance	[7]	0
Fair Value Assets, Gains (Losses) Included In Earnings	[7]	15
Fair Value Assets, Gains (Losses) Included in Other Comprehensive Income	[7]	0
Fair Value Assets, Purchases	[7]	0
Fair Value Assets, Issuances	[7]	0
Fair Value Assets, Settlements	[7]	0
Fair Value Assets, Transfers Into Level 3	[7]	0
Fair Value Assets, Transfers Out of Level 3	[7]	0
Fair Value Assets, Ending Balance	[7]	15	$ 0
Fair Value Assets, Current Period Unrealized Gains (Losses)	[7]	$ 15

[1] Level 3 net derivatives included derivative assets of $301 million and derivative liabilities of $152 million at December 31, 2017 and derivative assets of $391 million and derivative liabilities of $208 million at December 31, 2016. Gains (losses) on derivatives, net are predominantly included in trading revenue in the consolidated statement of income (loss).

[2] Consists of swap agreements entered into in conjunction with the sales of certain Visa Class B Shares.

[3] Gains (losses) on trading assets, excluding derivatives are included in trading revenue in the consolidated statement of income (loss).

[4] Realized gains (losses) on securities available-for-sale are included in other securities gains, net in the consolidated statement income. Unrealized gains (losses) on securities available-for-sale are included in other comprehensive income (loss).

[5] During the fourth quarter of 2016, we sold our remaining residential mortgage servicing rights portfolio to a third party. Gains (losses) on residential mortgage servicing rights were included in residential mortgage banking revenue (expense) in the consolidated statement of income (loss).

[6] See Note 15, "Fair Value Option," for additional information. Beginning January 1, 2017, unrealized gains (losses) on fair value option liabilities attributable to our own credit spread is recorded in other comprehensive income (loss).

[7] Represents contingent consideration receivable associated with the sale of a portion of our Private Banking business. Gains (losses) associated with this transaction are included in other income (loss) in the consolidated statement of income (loss).