Financial Instruments Financial Instruments at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	$ 2,436	$ 3,029
Derivative Asset, Noncurrent	803	1,822
Derivative Liability, Current	(322)	(56,771)	[1]
Derivative Liability, Noncurrent	(112,076)	(184,048)	[1]
Derivative Assets (Liabilities), at Fair Value, Net	(109,159)	(235,968)
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	$ 0	43,575
Distribution Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities		$ 25,700

[1] Includes $25.7 million of cash held on deposit to collateralize certain distribution financial instruments, which were used to offset current and noncurrent risk management liabilities at September 30, 2016.