Earnings Per Share - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount	200,000	200,000	200,000	200,000
Additional authorized repurchase amount	$ 68.2		$ 68.2
Number of shares repurchased	0	0	0	241,270
Repurchase of common stock, value				$ 6.8
Common Stock [Member]
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share amount			200,000