Derivatives and Hedge Accounting Activities (Schedule of Amounts Recorded on Balance Sheet Related to Cumulative Basis Adjustments for Fair Value Hedges) (Detail) - Designated as Hedging Instrument - Fair Value Hedging - Long-term Debt - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Carrying Amount of the Hedged Asset (Liability)	[1]	$ (1,153)	$ (1,153)
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Assets (Liabilities)	[2]	$ (3)	$ (3)

[1] Includes $(1.2) billion related to discontinued hedging relationships at both June 30, 2021 and December 31, 2020.

[2] Includes $(3) million of hedging adjustments on discontinued hedging relationships at both June 30, 2021 and December 31, 2020.