Earnings Per Share (Reconciliation of Net Earnings to Net Earnings Per Share Basic and Diluted) (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
Earnings Per Share
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 shares outstanding									66,432	68,392	68,880
Dilutive effect of stock options and restricted stock									1,344	1,210	1,427
Diluted shares outstanding									67,776	69,602	70,307
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