Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Thousands	Jan. 31, 2016	Oct. 31, 2015
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	$ 223,277	$ 206,956
Cardinal Pipeline Company
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	14,928	15,083
Pine Needle Company
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	18,118	18,396
South Star Energy Services
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	46,207	41,325
Hardy Storage
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	40,389	39,706
Constitution Pipeline Company
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	88,968	82,403
Atlantic Coast Pipeline
Variable Interest Entity [Line Items]
Total equity method investments in non-utility activities	$ 14,667	$ 10,043