Stock Repurchase Program - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 16, 2016
Equity, Class of Treasury Stock [Line Items]
Number of shares repurchased	3,833,000	2,977,000	1,494,000
Average price paid per share	$ 88.16	$ 78.54	$ 77.73
Total cost	$ 337,910	$ 233,793	$ 116,132
Remaining number of shares authorized to be repurchased under stock repurchase program	2,100,000
Subsequent Event [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, number of shares authorized to be repurchased				5,000,000