Common Stock, Restricted Stock Activity (Details) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Restricted Stock Activity
Nonvested, beginning of year	105,540	70,584	38,388
Weighted average price, nonvested, beginning of year	$ 61.69	$ 49.33	$ 38.33
Grants in Period	74,848	63,900	58,350
Weighted average price, grants in period	$ 101.97	$ 71.14	$ 55.05
Vested in Period	(48,072)	(25,934)	(25,994)
Weighted average price, vested in period	$ 102.09	$ 52.46	$ 45.99
Forfeited in Period	(2,920)	(3,010)	(160)
Weighted average price, forfeited in period	$ 63.49	$ 51.92	$ 39.27
Nonvested, end of year	129,396	105,540	70,584
Weighted average price, nonvested, end of year	$ 69.94	$ 61.69	$ 49.33