Financial Instruments and Fair Value Measurement (Details 2) (USD $)	Mar. 31, 2013	Sep. 30, 2012
Significant Other Observable Inputs (Level 2)
Supplemental fair value information about fixed-rate debt
Carrying value of fixed-rate debt	$ 235,000	$ 235,000
Fair value of fixed-rate debt	248,800	252,700
Recurring basis | Total Measure at Fair Value
Assets
Cash and cash equivalents	172,993,000
Equity securities	492,776,000
Other current assets	7,606,000
Other assets	2,000,000
Total assets measured at fair value	675,375,000
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash and cash equivalents	172,993,000
Equity securities	492,776,000
Other current assets	7,356,000
Other assets	2,000,000
Total assets measured at fair value	675,125,000
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Other current assets	250,000
Total assets measured at fair value	$ 250,000