OTTI Losses on Available for Sale Securities (Detail) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017	[3]	Sep. 30, 2017
Available-for-sale Securities	[1],[2]	$ 30,984	$ 30,947
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held		$ 0			$ 22

[1] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets. Reclassifications have been made to previously reported amounts for comparability.

[2] Includes securities AFS pledged as collateral where counterparties have the right to sell or repledge the collateral of $164 million and $223 million at September 30, 2018 and December 31, 2017, respectively.

[3] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets. Reclassifications have been made to previously reported amounts for comparability. See Note 9, "Other Assets," for additional information.