Operations and Significant Accounting Policies - Sale of U.S. Water Services (Details) $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Business Segments [Line Items]
Proceeds from Sale of U.S. Water Services - Net of Transaction Costs and Cash Retained	$ 270.0
Gain on Sale of U.S. Water Services, After-tax	$ 13.2

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