Shareholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) Stockholder $ / shares shares	Sep. 30, 2018 $ / shares shares	Sep. 30, 2019 USD ($) Stockholder $ / shares shares	Sep. 30, 2018 $ / shares shares	Dec. 31, 2018 USD ($)
Equity [Line Items]
Dividend payable, per share | $ / shares	$ 0.25	$ 0.25	$ 0.25	$ 0.25
Accrued dividends | $	$ 3.8		$ 3.8		$ 0.2
Ordinary Shares A
Equity [Line Items]
Shares repurchased	0	0	27,028	45,233
Number of shareholders | Stockholder	225		225
Ordinary Shares B
Equity [Line Items]
Shares repurchased	0	0	0	0