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Aggregate cash payments for a combination of transactions that are classified as investing activities in which assets, which may include securities, other types of investments, or productive assets, are purchased from third-party sellers. This element can be used by entities to aggregate payments for all asset purchases that are classified as investing activities.

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Variable Interest Entities (Narrative) (Details) $ in Millions									12 Months Ended
	Dec. 31, 2025 USD ($) Rate MW	Oct. 31, 2025 USD ($)	Oct. 30, 2025 USD ($)	Oct. 28, 2025 USD ($) Rate	Jun. 18, 2025 USD ($)	May 31, 2025 USD ($)	Feb. 03, 2025 USD ($)	Jan. 15, 2025 USD ($)	Dec. 31, 2025 USD ($) Rate MW	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jan. 31, 2024	Jun. 17, 2023 Rate
Variable Interest Entity [Line Items]
Wind Power Purchase Agreement, Purchase Percentage \| Rate	100.00%								100.00%
Milestone and final payments to renewable generation asset developers									$ 1,098.7	$ 482.0	$ 761.4
Income Taxes									203.8	158.1	139.5
Payments to Acquire Assets, Investing Activities	$ 3.6		$ 4.2		$ 262.4	$ 141.4	$ 217.6	$ 336.6
Business Combination, Price of Acquisition, Expected				$ 35.2
Business Combination, Transaction Cost, Excluding Separately Recognized Transaction										54.7
Proceeds from Contributed Capital		$ 175.0							344.9	2,160.0
Redeemable Noncontrolling Interest, Equity, Other, Carrying Amount										1,360.0
Proceeds from (Payments to) Noncontrolling Interests									154.4	99.5	2,170.7
Investment Company, Committed Capital				$ 1,325.0
Payments to Noncontrolling Interests									74.6	50.3	$ 0.0
Blackstone Investor
Variable Interest Entity [Line Items]
Proceeds from Contributed Capital									$ 76.9
NIPSCO Holdings II
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent \| Rate				19.90%									19.90%
Subsidiary, Ownership Percentage, Noncontrolling Owner				14.90%								4.50%
NiSource
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent	80.10%			80.10%					80.10%
Generation Holdings II
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent \| Rate				17.50%
Blackstone Investor
Variable Interest Entity [Line Items]
Subsidiary, Ownership Percentage, Parent \| Rate				19.90%
Rosewater
Variable Interest Entity [Line Items]
Nameplate Capacity \| MW	102								102
Indiana Crossroads Wind
Variable Interest Entity [Line Items]
Nameplate Capacity \| MW	302								302
Indiana Crossroads Solar
Variable Interest Entity [Line Items]
Nameplate Capacity \| MW	200								200
Dunns Bridge I
Variable Interest Entity [Line Items]
Nameplate Capacity \| MW	265								265
Consolidated Variable Interest Entities
Variable Interest Entity [Line Items]
Income Taxes										$ 63.5