Rights Agreement - Additional Information (Detail) - $ / shares		12 Months Ended
	May 18, 2016	Dec. 31, 2018	Dec. 31, 2017
Class Of Warrant Or Right [Line Items]
Conversion basis of dividend distribution		one preferred share purchase right (a “Right”) for each outstanding share of common stock
Common stock, par value	$ 0.01	$ 0.01	$ 0.01
Dividend payable date		May 31, 2016
Preferred stock, par value		$ 0.01	$ 0.01
Common stock acquisition beneficial ownership percentage	4.99%
Series A Junior Participating Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Preferred stock, par value	$ 0.01
Purchase price of one one-hundredth of preferred shares	$ 13.86