CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Utility Plant
Plant in Service	$ 6,020,469	$ 5,780,805
Utility Plant Under Capital Leases	248,635	84,870
Construction Work in Progress	258,965	160,288
Total Utility Plant	6,528,069	6,025,963
Accumulated Depreciation and Amortization	(2,293,783)	(2,193,656)
Accumulated Amortization of Capital Lease Assets	(73,646)	(63,605)
Total Utility Plant, Net	4,160,640	3,768,702
Investments and Other Property	50,952	51,260
Current Assets
Cash and Cash Equivalents	138,114	37,701
Accounts Receivable, Net	172,367	137,932
Fuel Inventory	22,783	25,059
Materials and Supplies	107,990	103,981
Regulatory Assets	106,725	93,960
Derivative Instruments	3,929	3,187
Other	25,571	10,777
Total Current Assets	577,479	412,597
Regulatory and Other Assets
Regulatory Assets	293,078	293,551
Derivative Instruments	8,402	8,826
Other	68,656	55,313
Total Regulatory and Other Assets	370,136	357,690
Total Assets	5,159,207	4,590,249
Capitalization
Common Stock (No Par Value, 75,000,000 Shares Authorized, 32,139,434 Shares Outstanding as of December 31, 2018 and 2017)	1,346,539	1,296,539
Capital Stock Expense	(6,357)	(6,357)
Retained Earnings	484,277	380,076
Accumulated Other Comprehensive Loss	(4,714)	(6,226)
Total Common Stock Equity	1,819,745	1,664,032
Preferred Stock (No Par Value, 1,000,000 Shares Authorized, None Outstanding as of December 31, 2018 and 2017)	0	0
Capital Lease Obligations	19,773	28,519
Long-Term Debt, Net	1,615,252	1,354,423
Total Capitalization	3,454,770	3,046,974
Current Liabilities
Current Maturities of Long-Term Debt	0	100,000
Borrowings Under Revolving Credit Facility	0	35,000
Capital Lease Obligations	172,510	10,749
Accounts Payable	133,012	97,367
Accrued Taxes Other than Income Taxes	41,686	40,706
Accrued Employee Expenses	34,339	30,929
Accrued Interest	17,927	14,750
Regulatory Liabilities	95,094	89,024
Customer Deposits	27,650	24,865
Derivative Instruments	18,137	10,667
Other	21,555	18,119
Total Current Liabilities	561,910	472,176
Regulatory and Other Liabilities
Deferred Income Taxes, Net	369,705	300,258
Regulatory Liabilities	512,425	516,438
Pension and Other Postretirement Benefits	117,472	133,799
Derivative Instruments	19,361	17,907
Other	123,564	102,697
Total Regulatory and Other Liabilities	1,142,527	1,071,099
Commitments and Contingencies
Total Capitalization and Other Liabilities	$ 5,159,207	$ 4,590,249