Acquisitions (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 16, 2014
U.S. and Canadian Business of Comex [Member]
Business Acquisition [Line Items]
Recognized intangible assets					$ 4,696
Summary of pro-forma consolidated financial information
Net sales	3,150,571	2,959,162	8,560,121	8,083,123
Net income	326,240	257,149	733,144	609,651
Net income per common share:
Basic (in dollars per share)	$ 3.42	$ 2.53	$ 7.53	$ 5.96
Diluted (in dollars per share)	$ 3.35	$ 2.47	$ 7.39	$ 5.83
Administrative [Member]
Business Acquisition [Line Items]
Realized gain on final asset valuations	$ 6,198		$ 6,198