Schedule II (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	$ 1,644	$ 1,421	$ 1,472
Additions to allowance for doubtful accounts	1,568	2,003	2,546
Deductions to allowance for doubtful accounts	(1,361)	(1,780)	(2,597)
Allowance for doubtful accounts, ending balance	1,851	1,644	1,421
Allowance for Doubtful Accounts - Straight Line Rent [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	819	692	257
Additions to allowance for doubtful accounts	599	1,503	1,501
Deductions to allowance for doubtful accounts	(777)	(1,376)	(1,066)
Allowance for doubtful accounts, ending balance	641	819	692
Allowance for Doubtful Accounts - Accounts Receivable [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	753	624	928
Additions to allowance for doubtful accounts	969	500	1,045
Deductions to allowance for doubtful accounts	(556)	(371)	(1,349)
Allowance for doubtful accounts, ending balance	1,166	753	624
Allowance for Doubtful Accounts - Notes Receivable [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	72	105	287
Additions to allowance for doubtful accounts	0	0	0
Deductions to allowance for doubtful accounts	(28)	(33)	(182)
Allowance for doubtful accounts, ending balance	$ 44	$ 72	$ 105