Financing Receivables (Gross And Net Lease Investment) (Detail) - Energy Holdings [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Schedule of Financial Receivables [Line Items]
Lease Receivables (net of Non-Recourse Debt)	$ 274	$ 299
Estimated Residual Value of Leased Assets	55	55
Total Investment in Rental Receivables	329	354
Unearned and Deferred Income	(100)	(104)
Gross Investments in Leases	229	250
Deferred Tax Liabilities	(60)	(64)
Net Investments in Leases	$ 169	$ 186