Financial Instruments and Fair Value Measurement (Details) (USD $)	3 Months Ended	6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Available-for-sale securities
Number of limited partnerships in which the entity sold its shares		3
Realized gain on shares sold in three limited partnerships		$ 8,800,000
Level1
Non-qualified Supplemental Savings Plan
Assets held in Non-qualified Supplement Savings Plan, at Fair Value	13,200,000		10,500,000
Equity securities
Available-for-sale securities
Cost	66,448,000		68,434,000
Gross Unrealized Gains	205,068,000		237,214,000
Estimated Fair Value	271,516,000		305,648,000
Equity available-for-sale securities sold, fair value	23,300,000	0
Total gross realized gain on such sales of available-for-sale securities	$ 21,400,000