Real Estate Intangibles (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate Intangible Amortization [Abstract]
Rental income related to above/below market tenant leases, net	$ 875	$ 919	$ (2,746)
Property operating expenses related to above/below market ground leases, net	(1,231)	(1,241)	(1,272)
Depreciation and amortization related to in place lease intangibles and lease commissions	$ (145,132)	$ (132,141)	$ (115,855)