Stockholders Equity - Additional Information (Detail) - $ / shares			3 Months Ended	9 Months Ended
	Sep. 21, 2018	Aug. 09, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity [Abstract]
Common stock dividend paid per share	$ 0.07		$ 0.06	$ 0.21	$ 0.165
Common stock dividend per share declared		$ 0.07	$ 0.06	$ 0.21	$ 0.165
Dividend payable, date declared				Aug. 09, 2018
Dividend payable, date paid				Sep. 21, 2018