Earnings Per Share (Reconciliation of Net Earnings to Net Earnings Per Share Basic and Diluted) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share
Net earnings	$ 50,060	$ 43,753	$ 43,855	$ 43,784	$ 51,662	$ 46,001	$ 44,798	$ 23,383	$ 181,452	$ 165,844	$ 145,942
Basic shares outstanding									64,684	66,432	68,392
Dilutive effect of stock options and restricted stock									1,372	1,344	1,210
Diluted shares outstanding									66,056	67,776	69,602
Basic earnings per share	$ 0.79	$ 0.68	$ 0.67	$ 0.67	$ 0.79	$ 0.70	$ 0.67	$ 0.35	$ 2.81	$ 2.50	$ 2.13
Diluted earnings per share	$ 0.77	$ 0.66	$ 0.66	$ 0.66	$ 0.77	$ 0.69	$ 0.66	$ 0.34	$ 2.75	$ 2.45	$ 2.10