Ordinary and Preference Shares - Summary of Shares Issued and Outstanding (Detail) - $ / shares	Dec. 31, 2016	Mar. 31, 2016
Class Of Stock [Line Items]
Common stock, shares issued	29,511,775	25,408,950
Common stock, shares outstanding	29,511,775	25,408,950
Common stock, par value
Preferred stock, shares issued	666,665	666,665
Preferred stock, shares outstanding	666,665	666,665
Ordinary Shares [Member]
Class Of Stock [Line Items]
Common stock, shares issued	29,511,775	25,408,950
Common stock, shares outstanding	29,511,775	25,408,950
Common stock, par value
7% Cumulative Redeemable Preference Shares [Member]
Class Of Stock [Line Items]
Preferred stock, shares issued	666,665	666,665
Preferred stock, shares outstanding	666,665	666,665
Liquidation amount per share	$ 25.52	$ 24.34