Defense Logistics Agency (DLA) Disposition Services Contracts (Details) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2012
Defense Logistics Agency (DLA) Disposition Services Contracts
Profit-sharing distributions	$ 9,942,000	$ 11,385,000	$ 18,352,000	$ 23,872,000
Profit-sharing distributions accrued	4,314,000		4,314,000		4,041,000
Surplus contract
Defense Logistics Agency (DLA) Disposition Services Contracts
Number of renewal options			2
Term of renewal options			1 year
Usable surplus property to be purchased as a fixed percentage of DoD's original acquisition value			1.80%
Profits from resale of the property retained (as a percent)			100.00%
Scrap contract
Defense Logistics Agency (DLA) Disposition Services Contracts
Number of renewal options			3
Term of renewal options			1 year
Profits distributed to DLA Disposition Services (as a percent)			77.00%
Additional profit sharing distribution (as a percent)			2.00%
Performance incentive measurement period			12 months
Profit-sharing distributions	9,943,000	11,385,000	18,352,000	23,872,000
Profit-sharing distributions accrued	$ 4,314,000	$ 6,117,000	$ 4,314,000	$ 6,117,000
Number of consecutive quarterly periods in which performance ratio does not exceed benchmark ratios resulting in contract termination			2
Number of preceding months in which performance ratio does not exceed benchmark ratios resulting in contract termination			12 months