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Capital Disclosure of investment grade credit rating (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Investment [Line Items]
Comparable funds from operations to adjusted interest coverage, actual	4.5	4.8
Adjusted comparable funds from operations to adjusted net debt, actual	19.00%	20.80%
Adjusted net debt to comparable earnings before interest, taxes, depreciation, and amortization, actual	3.9	3.6
Percentage of dividends added to Comparable FFO before Interest to Adjusted Interest Coverage	50.00%
Percentage of preferred dividends deducted from Adjusted Comparable FFO to Adjusted Net Debt	50.00%
Percentage of preferred shares added to net debt in Adjusted Comparable FFO to Adjusted Net Debt	50.00%
Minimum
Investment [Line Items]
Comparable funds from operations to adjusted interest coverage, Target	4
Adjusted comparable funds from operations to adjusted net debt, Target	20
Adjusted net debt to comparable earnings before interest, taxes, depreciation, and amortization, Target	3.0
Maximum
Investment [Line Items]
Comparable funds from operations to adjusted interest coverage, Target	5
Adjusted comparable funds from operations to adjusted net debt, Target	25
Adjusted net debt to comparable earnings before interest, taxes, depreciation, and amortization, Target	3.5

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- Definition

Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Sentence Column A

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