REVENUE - TIMING OF REVENUE RECOGNITION - BALANCE SHEET (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Sep. 30, 2018
Customer accounts receivable
Billed	$ 174,670	$ 205,490
Unbilled revenues	7,413	7,199
Customers' credit	(19,493)	$ (27,325)
Customers accounts receivables & Customers' credit balances and deposits	162,590
Operating Segments | Natural Gas Distribution
Customer accounts receivable
Billed	60,852
Unbilled revenues	7,413
Customers' credit	(19,490)
Customers accounts receivables & Customers' credit balances and deposits	48,775
Operating Segments | Clean Energy Ventures
Customer accounts receivable
Billed	2,942
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	2,942
Operating Segments | Energy Services
Customer accounts receivable
Billed	108,372
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	108,372
Home Services and Other
Customer accounts receivable
Billed	2,504
Unbilled revenues	0
Customers' credit	(3)
Customers accounts receivables & Customers' credit balances and deposits	2,501
Eliminations
Customer accounts receivable
Billed	0
Unbilled revenues	0
Customers' credit	0
Customers accounts receivables & Customers' credit balances and deposits	$ 0