CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Utility Plant
Plant in Service	$ 5,959,013	$ 5,780,805
Utility Plant Under Capital Leases	248,635	84,870
Construction Work in Progress	234,994	160,288
Total Utility Plant	6,442,642	6,025,963
Accumulated Depreciation and Amortization	(2,263,742)	(2,193,656)
Accumulated Amortization of Capital Lease Assets	(70,693)	(63,605)
Total Utility Plant, Net	4,108,207	3,768,702
Investments and Other Property	51,339	51,260
Current Assets
Cash and Cash Equivalents	17,539	37,701
Accounts Receivable, Net	196,366	137,932
Fuel Inventory	18,666	25,059
Materials and Supplies	106,001	103,981
Regulatory Assets	110,329	93,960
Derivative Instruments	3,977	3,187
Other	26,650	10,777
Total Current Assets	479,528	412,597
Regulatory and Other Assets
Regulatory Assets	293,627	293,551
Derivative Instruments	4,910	8,826
Other	68,576	55,313
Total Regulatory and Other Assets	367,113	357,690
Total Assets	5,006,187	4,590,249
Capitalization
Common Stock (No Par Value, 75,000,000 Shares Authorized, 32,139,434 Shares Outstanding as of September 30, 2018 and December 31, 2017)	1,296,539	1,296,539
Capital Stock Expense	(6,357)	(6,357)
Retained Earnings	517,327	380,076
Accumulated Other Comprehensive Loss	(6,458)	(6,226)
Total Common Stock Equity	1,801,051	1,664,032
Preferred Stock (No Par Value, 1,000,000 Shares Authorized, None Outstanding as of September 30, 2018 and December 31, 2017)	0	0
Capital Lease Obligations	181,571	28,519
Long-Term Debt, Net	1,318,509	1,354,423
Total Capitalization	3,301,131	3,046,974
Current Liabilities
Current Maturities of Long-Term Debt	136,700	100,000
Borrowings Under Revolving Credit Facility	15,000	35,000
Capital Lease Obligations	10,713	10,749
Accounts Payable	130,396	97,367
Accrued Taxes Other than Income Taxes	62,960	40,706
Accrued Employee Expenses	25,346	30,929
Accrued Interest	14,815	14,750
Regulatory Liabilities	109,661	89,024
Customer Deposits	26,668	24,865
Derivative Instruments	23,822	10,667
Other	16,361	18,119
Total Current Liabilities	572,442	472,176
Regulatory and Other Liabilities
Deferred Income Taxes, Net	364,452	300,258
Regulatory Liabilities	494,353	516,438
Pension and Other Postretirement Benefits	125,339	133,799
Derivative Instruments	24,218	17,907
Other	124,252	102,697
Total Regulatory and Other Liabilities	1,132,614	1,071,099
Commitments and Contingencies
Total Capitalization and Other Liabilities	$ 5,006,187	$ 4,590,249