Financial Instruments and Fair Value Measurement (Details 2) (USD $)	Mar. 31, 2014	Sep. 30, 2013
Supplemental fair value information about fixed-rate debt
Carrying value of fixed-rate debt	$ 195,000,000	$ 195,000,000
Significant Other Observable Inputs (Level 2)
Supplemental fair value information about fixed-rate debt
Carrying value of fixed-rate debt	195,000,000	195,000,000
Fair value of fixed-rate debt	203,600,000	205,400,000
Recurring basis | Total Measure at Fair Value
Assets:
Cash and cash equivalents	584,979,000
Equity securities	271,516,000
Other current assets	31,174,000
Other assets	2,000,000
Total assets measured at fair value	889,669,000
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	584,979,000
Equity securities	271,516,000
Other current assets	30,924,000
Other assets	2,000,000
Total assets measured at fair value	889,419,000
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Other current assets	250,000
Total assets measured at fair value	$ 250,000