Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 16, 2018	Feb. 16, 2017	Oct. 22, 2015	Oct. 23, 2014
October 2014 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares							2,000,000
Number of shares repurchased by the Company			1,134,300
Value of shares repurchased by the Company			$ 45.2
Common stock repurchase program, termination date	Oct. 22, 2015
October 2015 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares						3,150,000
Number of shares repurchased by the Company		1,578,952
Value of shares repurchased by the Company		$ 53.3
Common stock repurchase program, termination date	Dec. 31, 2016
February 2017 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares					2,961,000
Number of shares repurchased by the Company	0
February 2018 Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased by the Company	0
February 2018 Stock Repurchase Program [Member] | Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Common stock repurchase program, authorized shares				2,900,000