Financial Instruments Financial Instruments at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2016		Sep. 30, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	$ 9,804		$ 9,232
Derivative Asset, Noncurrent	1,822		368
Derivative Liability, Current	(56,771)		(9,568)
Derivative Liability, Noncurrent	(184,048)		(110,539)
Derivative Assets (Liabilities), at Fair Value, Net	(229,193)		(110,507)
Regulated Distribution Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	3,029		378
Derivative Asset, Noncurrent	1,822		368
Derivative Liability, Current	(56,771)		(9,568)
Derivative Liability, Noncurrent	(184,048)		(110,539)
Derivative Assets (Liabilities), at Fair Value, Net	(235,968)		(119,361)
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	25,670		0
Cash Held In Margin Accounts Classified Current Risk Management Asset	0		0
Nonregulated Segment [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Asset, Current	6,775	[1]	8,854	[2]
Derivative Asset, Noncurrent	0		0
Derivative Liability, Current	0	[1]	0	[2]
Derivative Liability, Noncurrent	0	[1]	0	[2]
Derivative Assets (Liabilities), at Fair Value, Net	6,775		8,854
Cash Held in Margin Accounts	24,700		43,500
Cash Held In Margin Accounts Used to Offset Risk Management Liabilities	17,905		34,620
Cash Held In Margin Accounts Classified Current Risk Management Asset	$ 6,775		$ 8,854

[1] ncludes $24.7 million of cash held on deposit to collateralize certain nonregulated financial instruments. Of this amount, $17.9 million was used to offset current and noncurent risk management liabilities under master netting arrangements and the remaining $6.8 million is classified as current risk management assets.

[2] Includes $43.5 million of cash held on deposit to collateralize certain nonregulated financial instruments. Of this amount, $34.6 million was used to offset current and noncurrent risk management liabilities under master netting arrangements and the remaining $8.9 million is classified as current risk management assets.