Ordinary and Preference Shares - Summary of Shares Issued and Outstanding (Detail) - $ / shares	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Class Of Stock [Line Items]
Ordinary shares, shares issued	100,965,451		80,398,326
Ordinary shares, shares outstanding	100,965,451		80,398,326
Ordinary shares, par value
Preference shares, shares issued	666,665		666,665
Preference shares, shares outstanding	666,665		666,665
7% Cumulative Redeemable Preference Shares [Member]
Class Of Stock [Line Items]
Preference shares, shares issued	666,665		666,665
Preference shares, shares outstanding	666,665		666,665
Liquidation amount per share	$ 31.43		$ 30.64
Ordinary Shares [Member]
Class Of Stock [Line Items]
Ordinary shares, shares issued	100,965,451		80,398,326
Ordinary shares, shares outstanding	100,965,451	80,593,440	80,398,326	66,366,706	66,212,893	65,900,447
Ordinary shares, par value