Stock Repurchase Program - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Feb. 28, 2014
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, remaining number of shares authorized to be repurchased	1,568,497		1,500,000
Stock repurchase program, repurchase authorization	5,000,000		3,000,000
Treasury stock, shares, acquired	1,431,503	988,000
Treasury stock acquired, average cost per share	$ 75.87	$ 74.35
Purchase of treasury stock	$ 108,613	$ 73,457