CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Utility Plant
Plant in Service	$ 8,099,577	$ 8,035,444
Construction Work in Progress	531,459	475,391
Total Utility Plant	8,631,036	8,510,835
Accumulated Depreciation and Amortization	(2,605,695)	(2,570,157)
Total Utility Plant, Net	6,025,341	5,940,678
Investments and Other Property	69,130	70,080
Current Assets
Cash and Cash Equivalents	57,297	8,616
Accounts Receivable (Net of Allowance for Credit Losses of $11,263 and $11,676)	192,799	217,381
Fuel Inventory	27,237	34,475
Materials and Supplies	179,825	172,667
Regulatory Assets	112,782	147,389
Derivative Instruments	31,487	3,091
Other	32,381	30,450
Total Current Assets	633,808	614,069
Regulatory Assets	195,953	182,997
Derivative Instruments	29,675	31,614
Other Noncurrent Assets	136,232	134,196
Total Assets	7,090,139	6,973,634
Common Stock Equity:
Common Stock (No Par Value, 75,000,000 Shares Authorized, 32,139,434 Shares Outstanding as of March 31, 2024 and December 31, 2023)	1,696,539	1,696,539
Capital Stock Expense	(6,357)	(6,357)
Retained Earnings	1,214,102	1,162,921
Accumulated Other Comprehensive Loss	(3,783)	(3,829)
Total Common Stock Equity	2,900,501	2,849,274
Preferred Stock (No Par Value, 1,000,000 Shares Authorized, None Outstanding as of March 31, 2024 and December 31, 2023)	0	0
Long-Term Debt, Net	2,097,399	2,396,542
Total Capitalization	4,997,900	5,245,816
Current Liabilities
Current Maturities of Long-Term Debt, Net	299,647	0
Accounts Payable	145,357	137,002
Accrued Taxes Other than Income Taxes	72,813	57,291
Accrued Employee Expenses	29,816	39,466
Accrued Interest	28,463	16,541
Regulatory Liabilities	91,737	92,740
Customer Deposits	15,802	15,833
Derivative Instruments	40,848	25,828
Other	42,523	36,312
Total Current Liabilities	767,006	421,013
Deferred Income Taxes, Net	656,906	647,730
Regulatory Liabilities	391,492	396,061
Pension and Other Postretirement Benefits	83,515	81,241
Derivative Instruments	5,654	4,338
Other Noncurrent Liabilities	187,666	177,435
Total Liabilities	2,092,239	1,727,818
Commitments and Contingencies
Total Capitalization and Liabilities	$ 7,090,139	$ 6,973,634