Securities Available for Sale (Addition Information) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held		$ 0		$ 0		$ 0
Debt and Equity Securities, Gain (Loss)		(42)	$ 0	(42)	$ 1
Debt Securities, Available-for-sale, Restricted		3,400		3,400		3,300
Available-for-sale Securities	[1]	32,487		32,487		31,442
Federal Home Loan Bank (FHLB) of Atlanta stock (par value)	[2]	429		429		227
Federal Reserve Bank Stock	[2]	403		403		403
Mutual Fund Investments	[2]	67		67		79
Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities		0		0		0
Fair Value, Measurements, Recurring [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities		32,487		32,487		31,442
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities		$ 0		$ 0		$ 0

[1] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $212 million and $222 million at June 30, 2019 and December 31, 2018, respectively.

[2] Does not include equity securities held for trading purposes classified as Trading assets and derivative instruments or Trading liabilities and derivative instruments on the Company’s Consolidated Balance Sheets. See Note 4, “Trading Assets and Liabilities and Derivative Instruments,” for more information.