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Equity (Schedule of Stock Offering Program) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
At The Market Stock Offering [Line Items]
Stock Issued During Period, Shares, New Issues			24,964,000
Proceeds, net of fees (in millions)	$ 211.4	$ 244.4	$ 848.2
At The Market Program
At The Market Stock Offering [Line Items]
Stock Issued During Period, Shares, New Issues	8,459,430	8,422,498	8,883,014
Common Stock Issued Average Price Per Share	$ 23.60	$ 27.75	$ 26.85
Proceeds, net of fees (in millions)	$ 196.5	$ 229.1	$ 232.5

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