Leases ASC 840 (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Allowance For Doubtful Accounts [Roll Forward]
Allowance for doubtful accounts, beginning balance	$ 1,644
Additions to allowance for doubtful accounts	1,568
Deductions to allowance for doubtful accounts	(1,361)
Allowance for doubtful accounts, ending balance	1,851
Lessee Disclosure [Abstract]
Total rental property expense recorded for operating ground leases	2,500
Allowance for Doubtful Accounts - Straight Line Rent [Member]
Allowance For Doubtful Accounts [Roll Forward]
Allowance for doubtful accounts, beginning balance	819
Additions to allowance for doubtful accounts	599
Deductions to allowance for doubtful accounts	(777)
Allowance for doubtful accounts, ending balance	641
Allowance for Doubtful Accounts - Accounts Receivable [Member]
Allowance For Doubtful Accounts [Roll Forward]
Allowance for doubtful accounts, beginning balance	753
Additions to allowance for doubtful accounts	969
Deductions to allowance for doubtful accounts	(556)
Allowance for doubtful accounts, ending balance	1,166
Allowance for Doubtful Accounts - Notes Receivable [Member]
Allowance For Doubtful Accounts [Roll Forward]
Allowance for doubtful accounts, beginning balance	72
Additions to allowance for doubtful accounts	0
Deductions to allowance for doubtful accounts	(28)
Allowance for doubtful accounts, ending balance	$ 44