Total costs accrued as of the balance sheet date for environmental loss contingencies.

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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The capacity, in megawatts, of coal generation expected to be retired by 2020.

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The capital and operating costs needed to achieve the required level of reduction in emissions.

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Global temperature increases limit

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Represents the number of revisions to Mercury and Air Toxics Standards

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COMMITMENTS AND CONTINGENCIES - ENVIRONMENTAL MATTERS (Details) $ in Millions	1 Months Ended		6 Months Ended	12 Months Ended
	Apr. 30, 2019 degreecelsius	Dec. 31, 2018 USD ($) change	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($) MW
Manufactured gas plant remediation
Regulatory assets		$ 485.9	$ 485.6	$ 485.9
Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets		$ 108.3	$ 125.2	$ 108.3
Mercury and air toxics standards \| Electric
Air quality
Revisions to Mercury and Air Toxics Standards \| change		0
Climate Change \| Electric
Air quality
Company goal for percentage of carbon dioxide emissions reduction by 2030			40.00%
Long-term company goal for percentage of carbon dioxide emissions reduction by 2050			80.00%
Coal generation capacity retired in 2018 \| MW				300
Climate Change \| Electric \| Maximum
Air quality
Global temperature increases limit \| degreecelsius	2
Steam Electric Effluent Limitation Guidelines \| Electric
Water quality
Expected cost to achieve required emissions reduction			$ 20.0
Manufactured Gas Plant Remediation \| Natural gas
Manufactured gas plant remediation
Reserves for future remediation		$ 90.3	104.2	$ 90.3
Manufactured Gas Plant Remediation \| Natural gas \| Environmental remediation costs
Manufactured gas plant remediation
Regulatory assets		$ 108.3	$ 125.2	$ 108.3