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Common Equity (Changes in Shareowners' Equity) (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2024 | Mar. 31, 2023
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | $ 6,777 |
Beginning balance | 6,777 | $ 6,276
Net income attributable to common shareowners | 158 | 163
Net income | 158 | 163
Common stock dividends | (123) | (113)
Shareowner Direct Plan issuances | 6 | 6
Equity-based compensation plans and other | (2) | (3)
Other comprehensive income (loss), net of tax | 1 | (1)
Ending balance | 6,817 |
Ending balance | $ 6,817 | $ 6,328
Common stock dividends (in dollars per share) | $ 0.48 | $ 0.4525
Common Stock [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | $ 3 | $ 3
Ending balance | 3 | 3
Additional Paid-in Capital [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 3,030 | 2,777
Shareowner Direct Plan issuances | 6 | 6
Equity-based compensation plans and other | (3) | (3)
Ending balance | 3,033 | 2,780
Retained Earnings [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 3,756 | 3,509
Net income attributable to common shareowners | 158 | 163
Common stock dividends | (123) | (113)
Ending balance | 3,791 | 3,559
Accumulated Other Comprehensive Income (Loss) [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 1 | 0
Other comprehensive income (loss), net of tax | 1 | (1)
Ending balance | 2 | (1)
Shares in Deferred Compensation Trust [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | (13) | (13)
Equity-based compensation plans and other | 1 |
Ending balance | (12) | (13)
IPL [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 3,974 |
Beginning balance | 3,974 | 3,808
Net income | 63 | 72
Common stock dividends | (50) | (70)
Capital contributions from parent | 50 | 0
Ending balance | 4,037 |
Ending balance | 4,037 | 3,810
IPL [Member] | Common Stock [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 33 | 33
Ending balance | 33 | 33
IPL [Member] | Additional Paid-in Capital [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 2,887 | 2,807
Capital contributions from parent | 50 |
Ending balance | 2,937 | 2,807
IPL [Member] | Retained Earnings [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 1,054 | 968
Net income | 63 | 72
Common stock dividends | (50) | (70)
Ending balance | 1,067 | 970
WPL [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 3,897 |
Beginning balance | 3,897 | 3,491
Net income | 92 | 88
Common stock dividends | (49) | (46)
Capital contributions from parent | 55 | 180
Ending balance | 3,995 |
Ending balance | 3,995 | 3,713
WPL [Member] | Common Stock [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 66 | 66
Ending balance | 66 | 66
WPL [Member] | Additional Paid-in Capital [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 2,478 | 2,233
Capital contributions from parent | 55 | 180
Ending balance | 2,533 | 2,413
WPL [Member] | Retained Earnings [Member] |  |
Changes in Shareowners' Equity Roll Forward [Line Items] |  |
Beginning balance | 1,353 | 1,192
Net income | 92 | 88
Common stock dividends | (49) | (46)
Ending balance | $ 1,396 | $ 1,234

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