Business Acquisitions (Schedule of Unaudited Pro Forma Results) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Business Combinations
Net sales	$ 558,365	$ 483,759	$ 485,513	$ 408,339	$ 528,697	$ 460,241	$ 468,793	$ 407,896	$ 1,935,976	$ 1,865,627	$ 1,711,702
Net earnings	52,465	23,663	42,446	27,368	46,120	28,302	38,751	28,416	145,942	141,589	132,235
Basic earnings per share	$ 0.77	$ 0.35	$ 0.62	$ 0.40	$ 0.67	$ 0.41	$ 0.56	$ 0.41	$ 2.13	$ 2.06	$ 1.92
Diluted earnings per share	$ 0.76	$ 0.34	$ 0.61	$ 0.39	$ 0.66	$ 0.40	$ 0.55	$ 0.40	$ 2.10	$ 2.01	$ 1.89
Pro forma
Net sales									1,966,376	1,978,169
Net earnings									$ 152,271	$ 131,412
Basic earnings per share									$ 2.23	$ 1.91
Diluted earnings per share									$ 2.19	$ 1.87