Marketable Securities (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2015 USD ($) Security	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of securities below amortized cost basis	44
Number of securities	81
Proceeds from maturities of marketable securities | $	$ 38,028	$ 47,420	$ 63,089
Current Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, next twelve months, maximum year mature	1 year
Non-current Assets
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, year two through five, maximum year mature	3 years