Details of Selected Consolidated Balance Sheet Captions - Goodwill Detail Table (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2018 USD ($)
Goodwill [Roll Forward]
Goodwill beginning balance	$ 730,132
Deferred tax adjustments on prior acquisitions	287
Goodwill ending balance	730,419
Distribution
Goodwill [Roll Forward]
Goodwill beginning balance	587,080
Deferred tax adjustments on prior acquisitions	262
Goodwill ending balance	587,342
Pipeline and Storage
Goodwill [Roll Forward]
Goodwill beginning balance	143,052
Deferred tax adjustments on prior acquisitions	25
Goodwill ending balance	$ 143,077