Share Repurchase Program - Additional Information (Detail) - USD ($)	1 Months Ended		9 Months Ended
	Jan. 31, 2016	Jan. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Oct. 28, 2016	Jul. 31, 2014
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program authorized	$ 25,000,000	$ 35,000,000				$ 65,000,000
Common stock shares repurchased			93,516	238,201
Cost of common stock shares repurchased			$ 13,900,000	$ 20,000,000
Share Repurchase Program [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program period		2 years
New Share Repurchase Program [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program period	2 years
Subsequent Event [Member] | New Share Repurchase Program [Member]
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program additional authorized amount					$ 50,000,000