Ordinary and Preference Shares - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Sep. 15, 2020	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019	Jan. 29, 2015
7% Cumulative Redeemable Preference Shares [Member]
Class Of Stock [Line Items]
Subscriptions price, per share					$ 22.50
Ordinary Shares [Member]
Class Of Stock [Line Items]
Newly issued ordinary shares Issues	20,294,117	20,294,117	13,800,000	19,635,068
Newly issued ordinary price per share	$ 4.25
Proceeds from issuance of ordinary shares	$ 86.3
Underwriting discounts and other offering expenses	$ 5.6