Schedule II: Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 132,928		$ 121,473
Charged to Earnings	(60,835)		15,747
Acquired Properties	3,515		0
Uncollectible Accounts Written-off	(7,533)		(3,237)
Disposed Properties	(1,585)		(1,055)
Balance at End of Year	66,490		132,928
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	15,164		11,637
Charged to Earnings	10,708		7,207
Acquired Properties	3,515		0
Uncollectible Accounts Written-off	(7,533)		(3,237)
Disposed Properties	(9)		(443)
Balance at End of Year	21,845		15,164
Straight-line Rent Receivable Allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	117,764		109,836
Charged to Earnings	(71,543)	[1]	8,540
Acquired Properties	0		0
Uncollectible Accounts Written-off	0		0
Disposed Properties	(1,576)		(612)
Balance at End of Year	$ 44,645		$ 117,764

[1] ⁽¹⁾  Amounts charged to earnings primarily relate to termination of lease arrangements with Elmcroft in January 2018.