Real Estate and Lease Intangibles - Summary of the Effect of the Amortization for Above and Below Market Ground and Retail Lease Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate [Line Items]
Total amortization of above/below market lease intangibles	$ (3,828)	$ (3,426)	$ (3,382)
Ground Lease [Member] | Property and Maintenance [Member]
Real Estate [Line Items]
Total amortization of above/below market lease intangibles	(4,369)	(4,321)	(4,321)
Retail Lease [Member] | Rental Income [Member]
Real Estate [Line Items]
Total amortization of above/below market lease intangibles	$ 541	$ 895	$ 939