Supplemental Financial Information - Summary of Carrying Value of Investments in Equity-Accounted Investees (Detail) - USD ($) $ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Schedule of Equity Method Investments [Line Items] | ||
| Shareholding % | 0.00% | 0.00% |
| Amount | $ 13 | $ 146 |
| ASEN [Member] | ||
| Schedule of Equity Method Investments [Line Items] | ||
| Shareholding % | 0.00% | 40.00% |
| Amount | $ 0 | $ 66 |
| WeEn [Member] | ||
| Schedule of Equity Method Investments [Line Items] | ||
| Shareholding % | 0.00% | 49.00% |
| Amount | $ 0 | $ 65 |
| Others [Member] | ||
| Schedule of Equity Method Investments [Line Items] | ||
| Shareholding % | 0.00% | 0.00% |
| Amount | $ 13 | $ 15 |