Stock Based Compensation (Restricted Stock) (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified		1 Months Ended			3 Months Ended	12 Months Ended			3 Months Ended			1 Months Ended
	Sep. 30, 2013 2006 Plan	Feb. 28, 2013 Restricted Stock	Jan. 31, 2013 Restricted Stock	Jun. 30, 2012 Restricted Stock	Dec. 31, 2011 Restricted Stock	Sep. 30, 2013 Restricted Stock	Sep. 30, 2012 Restricted Stock	Sep. 30, 2011 Restricted Stock	Dec. 31, 2011 Restricted Stock Minimum	Dec. 31, 2011 Restricted Stock Maximum	Sep. 30, 2013 Restricted Stock Non Employee Director Stock Option Plan	Aug. 31, 2012 Restricted Stock 2006 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock issuable to eligible Board of Directors members annually						2,000
Maximum aggregate number of shares to be issued under the plan						150,000
Number of shares available for grant	435,711					16,379					33,117
Shares issued under the plan		16,000	500	2,000	26,000		16,000					45,000
Shares issued, price per share		$ 58.54	$ 42.54	$ 37.50			$ 37.50		$ 30.79	$ 32.12		$ 39.11
Vesting period				2 years	3 years	2 years						3 years
Vesting percentage per year				50.00%		50.00%						33.00%
Number of shares authorized	750,000
Shares vested					7,601
Unvested restricted stock outstanding						68,100	89,641
Compensation expense						$ 2.1	$ 0.7	$ 0.8