Commitments and Contingencies - Supplemental Balance Sheet Information (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Operating leases
Other assets	$ 14,349
Accrued expenses and other liabilities	1,421
Regulatory liabilities and other	12,885
Total	14,306
Finance leases
Utility plant	18,207
Accumulated depreciation and amortization	(9,352)
Net utility plant	8,855
Current maturities of long-term debt, net	670
Long-term debt, net	5,378
Total finance lease liabilities	$ 6,048
Weighted average remaining lease term
Operating leases	155 months
Finance leases	80 months
Weighted average discount rate
Operating leases	3.70%
Finance leases	5.50%