Financing Receivables (Narrative) (Detail) - USD ($) $ in Millions |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2018 |
Jun. 30, 2017 |
Mar. 31, 2017 |
|
| Schedule of Financial Receivables [Line Items] | |||
| Lease Receivable adjustment | $ 15 | $ 55 | |
| Residual Value Adjustment | $ 7 | ||
| Lease investment with non-investment grade counterparties, gross | $ 335 | ||
| Lease investment with non-investment grade counterparties, net of deferred taxes | $ (88) | ||
| Powerton Station [Member] | |||
| Schedule of Financial Receivables [Line Items] | |||
| Counterparties’ S&P Credit Ratings | BB- | ||