Financing Receivables (Narrative) (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Schedule of Financial Receivables [Line Items]
Lease investment with non-investment grade counterparties, gross	$ 235
Lease investment with non-investment grade counterparties, net of deferred taxes	$ (24)
Powerton Station [Member]
Schedule of Financial Receivables [Line Items]
Counterparties’ S&P Credit Ratings	BB