Earnings Per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Calculation of weighted average common shares and common equivalent shares outstanding
Net income	$ 4,266	$ 10,736	$ 11,431	$ 8,685	$ 3,589	$ 9,207	$ 8,702	$ 8,213	$ 35,118	$ 29,711	$ 14,082
Weighted average common share and common share equivalents:
Common Shares									12,735,520	12,441,313	12,062,627
Common share equivalents									100,719	131,334	323,409
Total weighted average common shares and common share equivalents									12,836,239	12,572,647	12,386,036
Basic	$ 0.33	$ 0.84	$ 0.90	$ 0.68	$ 0.28	$ 0.74	$ 0.71	$ 0.67	$ 2.76	$ 2.39	$ 1.17
Diluted	$ 0.33	$ 0.83	$ 0.89	$ 0.68	$ 0.28	$ 0.72	$ 0.69	$ 0.65	$ 2.74	$ 2.36	$ 1.14