Commitments and Contingencies - Supplemental Balance Sheet Information (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Operating leases
Other assets	$ 14,241
Accrued expenses and other liabilities	1,309
Regulatory liabilities and other	12,897
Total	14,206
Finance leases
Utility plant	18,207
Accumulated depreciation and amortization	(9,059)
Net utility plant	9,148
Current maturities of long-term debt, net	660
Long-term debt, net	5,550
Total finance lease liabilities	$ 6,210
Weighted average remaining lease term
Operating leases	160 months
Finance leases	83 months
Weighted average discount rate
Operating leases	3.70%
Finance leases	5.50%