Indebtedness debt covenants (Details)	12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2016 USD ($)
debt covenants [Line Items]
Debt Instrument, Debt Covenant, Debt Service Coverage Ratio	1.87
dividend restriction AFFO	95.00%
Line of Credit Facility, Maximum Borrowing Capacity		$ 200,000,000
minimum equity debt covenants	$ 687,000,000
equity raise above min equity required	75.00%
total debt covenant min equity	$ 1,209,000,000
maximum dividends debt covenant	158,300,000
Minimum Net Worth Required for Compliance	$ 1,935,000,000
debt yield	10.31%
payout ratio	94.30%
Total leverage ratio	58.30%