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, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Business Combinations
Net sales	$ 565,447	$ 524,284	$ 482,467	$ 429,042	$ 558,365	$ 483,759	$ 485,513	$ 408,339	$ 2,001,240	$ 1,935,976	$ 1,865,627
Net earnings	51,662	46,001	44,798	23,383	52,465	23,663	42,446	27,368	165,844	145,942	141,589
Basic earnings per share	$ 0.79	$ 0.70	$ 0.67	$ 0.35	$ 0.77	$ 0.35	$ 0.62	$ 0.40	$ 2.50	$ 2.13	$ 2.06
Diluted earnings per share	$ 0.77	$ 0.69	$ 0.66	$ 0.34	$ 0.76	$ 0.34	$ 0.61	$ 0.39	$ 2.45	$ 2.10	$ 2.01
Pro forma
Net sales									2,001,240	1,966,376	1,978,169
Net earnings									$ 167,047	$ 152,431	$ 131,384
Basic earnings per share									$ 2.51	$ 2.23	$ 1.91
Diluted earnings per share									$ 2.46	$ 2.19	$ 1.87