Financing Receivables (Schedule Of Lease Receivables, Net Of Nonrecourse Debt, Associated With Leveraged Lease Portfolio Based On Counterparty Credit Rating) (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	$ 546	$ 629
Energy Holdings [Member]
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	546
Energy Holdings [Member] | Counterparties' Credit Rating (S&P), AA [Member]
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	15
Energy Holdings [Member] | Counterparties' Credit Rating (S&P), BBB plus, BBB, BBB minus [Member]
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	316
Energy Holdings [Member] | Standard & Poor's, BB minus Rating [Member]
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	133
Energy Holdings [Member] | Standard & Poor's, CCC- Rating [Member]
Guarantor Obligations [Line Items]
Lease Receivables, Net of Non-Recourse Debt	$ 82