Issued Capital and Preference Shares - Summary of Issued Capital and Preference Shares (Parenthetical) (Detail) - $ / shares |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Ordinary shares [Member] | ||
| Disclosure of classes of share capital [Line Items] | ||
| Par value | $ 0.1 | $ 0.1 |