Summary of Significant Accounting Policies - Amortization of Deferred Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Deferred Charges	$ 5,552	$ 4,379
Credit Facility Financing Costs [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Deferred Charges	143	101
Leasing Costs [Member]
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Deferred Charges	81	43
Lease Intangibles (In-place)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Deferred Charges	2,052	1,992
Lease Intangibles (Above-Market)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Deferred Charges	4,374	3,344
Lease Intangibles (Below-Market)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Amortization of Below Market Lease	$ (1,098)	$ (1,101)