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Schedule 1 - Condensed Financial Information of Registrant - Condensed Statements of Income, Parent Company (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Income |  |  |
Other Income (Expense), net | $ 2,900 | $ 6,055 | $ 5,112
Expense |  |  |
Total Operating Expenses | 947,136 | 742,221 | 784,623
Interest Charges | 37,771 | 34,447 | 31,411
Nonservice Cost Components of Postretirement Benefits | 2,016 | 3,437 | 4,293
Income Tax Expense (Benefit) | (36,052) | (20,206) | (17,441)
Net Income | 176,769 | 95,851 | 86,847
OTC |  |  |
Income |  |  |
Equity Income in Earnings of Subsidiaries | 188,375 | 106,379 | 93,731
Interest Income from Subsidiaries | 2,826 | 2,859 | 3,063
Other Income (Expense), net | 1,290 | 1,317 | 1,566
Total Income | 192,491 | 110,555 | 98,360
Expense |  |  |
Total Operating Expenses | 14,825 | 14,007 | 10,529
Interest Charges | 4,727 | 4,599 | 4,863
Interest Charges from Subsidiaries | 3 | 136 | 306
Nonservice Cost Components of Postretirement Benefits | 1,097 | 1,150 | 1,297
Total Expense | 20,652 | 19,892 | 16,995
Income Before Income Taxes | 171,839 | 90,663 | 81,365
Income Tax Expense (Benefit) | 4,930 | 5,188 | 5,482
Net Income | $ 176,769 | $ 95,851 | $ 86,847

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