Stock Repurchase Program - Additional Information (Detail) - USD ($)	1 Months Ended	6 Months Ended	14 Months Ended
	Sep. 10, 2015	Aug. 01, 2015	Aug. 01, 2015	May. 22, 2014
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, Expiration date		May 31, 2016
Repurchase and retirement of common stock, shares			374,000
Repurchase and retirement of common stock		$ 2,514,000	$ 7,300,000
Stock repurchase program, remaining authorized repurchase amount		$ 22,700,000	$ 22,700,000
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchase and retirement of common stock, shares	36,000
Repurchase and retirement of common stock	$ 843,000
Maximum [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, Authorized amount				$ 30,000,000