Securities Available for Sale (Addition Information) (Detail) - USD ($) $ in Millions		Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted		$ 3,300	$ 3,300
Available-for-sale Securities	[1]	31,853	31,442
Federal Home Loan Bank (FHLB) of Atlanta stock (par value)	[2]	366	227
Federal Reserve Bank Stock	[2]	403	403
Mutual Fund Investments	[2]	65	79
Fair Value, Inputs, Level 3 [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities		0	0
Fair Value, Measurements, Recurring [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities		31,853	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

[1] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $210 million and $222 million at March 31, 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.