Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 48,592	$ 20,502
Restricted Cash and Cash Equivalents	5	6,120
Accounts Receivable, after Allowance for Credit Loss, Current	160,735	165,193
Inventory, Net	80,610	95,506
Regulatory assets	47,675	45,430
Income Taxes Receivable, Current	15,270	24,384
Other Assets, Current	41,441	17,842
Total current assets	394,328	374,977
UTILITY PLANT:
Property, Plant and Equipment, Gross	6,559,864	6,530,395
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	2,690,636	2,643,695
Utility plant in service - net	3,869,228	3,886,700
Construction in Progress, Gross	230,199	209,584
Total net property, plant and equipment	4,099,427	4,096,284
OTHER ASSETS:
Intangible Assets, Net (Excluding Goodwill)	56,713	59,141
Regulatory assets	385,995	392,801
Other assets - net	48,792	46,716
Assets, Noncurrent	491,500	498,658
TOTAL ASSETS	4,985,255	4,969,919
Debt, Current	184,945	169,907
CURRENT LIABILITIES:
Accounts payable	122,399	127,089
Accrued taxes	37,831	26,620
Interest Payable, Current	42,914	31,733
Customer deposits	26,685	27,929
Regulatory Liability, Current	10,968	30,036
Accrued Liabilities and Other Liabilities	14,426	19,453
Total current liabilities	440,168	432,767
NON-CURRENT LIABILITIES:
Long-term debt (Note 4)	2,556,848	2,556,278
Deferred income tax liabilities	288,825	275,714
Taxes Payable	7,552	7,458
Regulatory Liability, Noncurrent	835,269	839,360
Accrued pension and other postretirement benefits	5,380	5,334
Asset retirement obligations	195,704	195,236
Other non-current liabilities	13,683	13,785
Total non-current liabilities	3,926,772	3,956,380
Liabilities	4,366,940	4,389,147
Common shareholders' equity:
Additional Paid in Capital	589,007	588,966
Accumulated Other Comprehensive Income (Loss), Net of Tax	(13,826)	(43,420)
Accumulated deficit	(16,650)	(24,558)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	558,531	520,988
Cumulative preferred stock of subsidiary	59,784	59,784
Total common shareholders' equity	618,315	580,772
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	4,985,255	4,969,919
Derivative Liability, Noncurrent	23,511	63,215
Accounts Receivable, Allowance for Credit Loss, Current	1,966	3,155
Accounts receivable and unbilled revenue, allowance for doubtful accounts	$ 1,966	$ 3,155