Financial Instruments and Fair Value Measurement (Details 2) (USD $)	Dec. 31, 2014	Sep. 30, 2014
Supplemental fair value information about long-term fixed-rate debt
Carrying value of long-term fixed-rate debt	$ 80,000,000	$ 80,000,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring basis
Assets:
Cash and cash equivalents	251,636,000
Equity securities	153,409,000
Other current assets	36,136,000
Other assets	2,000,000
Total assets measured at fair value	443,181,000
Significant Other Observable Inputs (Level 2)
Supplemental fair value information about long-term fixed-rate debt
Carrying value of long-term fixed-rate debt	80,000,000	80,000,000
Fair value of long-term fixed-rate debt	82,500,000	84,300,000
Significant Other Observable Inputs (Level 2) | Recurring basis
Assets:
Other current assets	250,000
Total assets measured at fair value	250,000
Total Measure at Fair Value | Recurring basis
Assets:
Cash and cash equivalents	251,636,000
Equity securities	153,409,000
Other current assets	36,386,000
Other assets	2,000,000
Total assets measured at fair value	$ 443,431,000