Stock Repurchase Program (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Class of Stock Disclosures [Abstract]
Number of shares repurchased	2,700	2,793
Average price paid per share	$ 90.11	$ 86.92
Total cost	$ 243,288	$ 242,748