Regulatory Matters - Assets and Liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2016	Oct. 31, 2015
Regulatory Liabilities [Line Items]
Regulatory liabilities - current	$ 5,680	$ 13,367
Regulatory liabilities - noncurrent	590,400	590,301
Regulatory liabilities, Total	596,080	603,668
Regulatory Assets [Line Items]
Regulatory assets - current	61,815	10,936
Regulatory assets - noncurrent	322,310	196,726
Regulatory assets, Total	384,125	207,662
Amounts due to customers
Regulatory Liabilities [Line Items]
Regulatory liabilities - current	5,680	13,367
Regulatory cost of removal
Regulatory Liabilities [Line Items]
Regulatory liabilities - noncurrent	526,299	521,478
Deferred income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities - noncurrent	64,019	68,738
Amounts not yet recognized as a component of pension and other retirement benefit costs
Regulatory Liabilities [Line Items]
Regulatory liabilities - noncurrent	82	85
Unamortized debt expense on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets - current	238	238
Regulatory assets - noncurrent	4,607	4,666
Amounts due from customers
Regulatory Assets [Line Items]
Regulatory assets - current	22,956	0
Environmental costs
Regulatory Assets [Line Items]
Regulatory assets - current	1,522	1,513
Regulatory assets - noncurrent	4,587	5,107
Deferred operations and maintenance expenses
Regulatory Assets [Line Items]
Regulatory assets - current	860	847
Regulatory assets - noncurrent	3,777	3,997
Deferred pipeline integrity expenses
Regulatory Assets [Line Items]
Regulatory assets - current	3,470	3,470
Regulatory assets - noncurrent	29,767	29,824
Deferred pension and other retirement benefit costs
Regulatory Assets [Line Items]
Regulatory assets - current	2,757	2,757
Regulatory assets - noncurrent	18,887	17,861
Amounts not yet recognized as a component of pension and other retirement benefit costs
Regulatory Assets [Line Items]
Regulatory assets - noncurrent	113,197	114,854
Regulatory cost of removal
Regulatory Assets [Line Items]
Regulatory assets - noncurrent	19,363	19,087
Robeson liquefied natural gas (LNG) development costs
Regulatory Assets [Line Items]
Regulatory assets - current	382	381
Regulatory assets - noncurrent	32	127
Derivatives - gas supply contracts held for utility operations
Regulatory Assets [Line Items]
Regulatory assets - current	28,300	0
Regulatory assets - noncurrent	127,000	0
Other
Regulatory Assets [Line Items]
Regulatory assets - current	1,330	1,730
Regulatory assets - noncurrent	$ 1,093	$ 1,203