Capital Structure - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2014	Jan. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred stock, shares authorized			5,000,000	5,000,000
Preferred stock, par value			$ 0.001	$ 0.001
Preferred stock, shares issued			0	0
Preferred stock, shares outstanding			0	0
Number of shares of common stock authorized to issue			125,000,000	125,000,000
Common stock, par value per share			$ 0.001	$ 0.001
Number of votes entitled for each share held			one
Debt instrument percentage			2.00%	2.00%
Amount of stock authorized for repurchase	$ 35.0
Number of shares repurchased	1,147,540
Shares of common stock in treasury			1,251,297	1,251,000
Shares sold to public, shares		3,110,449
Shares sold to public, per share		$ 26.64
Proceeds from sale of shares		$ 78.0
Senior Notes [Member]
Class of Stock [Line Items]
Debt instrument percentage	2.00%