Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2013 Environmental Issue [Member]	Dec. 31, 2013 Environmental Issue [Member] PNG MGP [Member]	Dec. 31, 2013 Environmental Remediation Expense [Member] CPG MGP [Member]	Dec. 31, 2013 Environmental Remediation Expense [Member] PNG MGP [Member]	Dec. 31, 2013 CPG and PNG COAs [Member]	Dec. 31, 2012 CPG and PNG COAs [Member]
Commitments and Contingencies [Line Items]
Environmental expenditures cap during calendar year			$ 1,800	$ 1,100
Option to termination agreement by either party effective at end of any two-year period beginning with the original effective date in March 2004 (in years)		2 years
Accrual for environmental loss contingencies					$ 16,900	$ 14,965
Base year for determination of investigation and remediation cost (in years)	5 years