Shareholders' Equity Additional Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 27, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Subsequent Event [Line Items]
Repurchase and retirement of common stock				$ 154,381
Repurchase and retirement of common stock (shares)				1,803
Shares remaining available for repurchases (shares)		8,568		8,568
Cash dividend paid during period, per share (in dollars per share)		$ 0.55	$ 0.53	$ 1.65	$ 1.59
Dividends declared (in dollars per share)	$ 0.55
Common stock excluded from calculation of diluted earnings per share (shares)		1,786	1,087	1,736	971