Capital Stock - Additional Information (Details) - USD ($)	3 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2019	May 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Common stock, shares authorized	500,000,000		500,000,000
Common stock, par value	$ 0.005		$ 0.005
Common stock, voting rights			each outstanding share of common stock is entitled to one vote
Common stock, shares issued	11,432,178		11,432,178		10,864,722
Common stock, shares outstanding	11,432,178		11,432,178		10,864,722
Preferred stock, shares authorized	20,000,000		20,000,000
Preferred stock, par value	$ 0.005		$ 0.005
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Repurchase of common stock	120,000	0
Average price per share	$ 28.86
Repurchase of common stock amount	$ 3,466,000
Amount authorized to repurchase remaining common stock	$ 11,500,000		$ 11,500,000
Maximum
Class Of Stock [Line Items]
Amount approved for common stock repurchase				$ 15,000,000