Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011
Schedule of original cost and fair value of investments by contractual maturity
Amortized Cost	$ 42,064
Fair market value of held-to-maturity debt securities	42,320	3,100
One Year [Member]
Schedule of original cost and fair value of investments by contractual maturity
Amortized Cost	13,509
Fair market value of held-to-maturity debt securities	13,519
One to five years [Member]
Schedule of original cost and fair value of investments by contractual maturity
Amortized Cost	24,346
Fair market value of held-to-maturity debt securities	24,545
Five years or more [Member]
Schedule of original cost and fair value of investments by contractual maturity
Amortized Cost	4,209
Fair market value of held-to-maturity debt securities	$ 4,256