Lease Intangibles - Scheduled Amortization of Acquired Lease Intangible Assets and Assumed Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Acquired Lease Intangibles [Abstract]
Net Increase In Lease Revenues, Total	$ 97,184	$ 103,841
Amortizable Intangible Assets, Net Carrying Amount	(112,249)	(127,571)
In-place lease intangible assets
Acquired Lease Intangibles [Abstract]
2018 (Remainder), Net Increase In Lease Revenues	2,246
2019, Net Increase In Lease Revenues	9,462
2020, Net Increase In Lease Revenues	8,938
2021, Net Increase In Lease Revenues	7,720
2022, Net Increase In Lease Revenues	7,405
Thereafter, Net Increase In Lease Revenues	56,320
Net Increase In Lease Revenues, Total	92,091
2018 (Remainder), Increase to Amortization	(7,724)
2019, Increase to Amortization	(25,137)
2020, Increase to Amortization	(18,264)
2021, Increase to Amortization	(13,298)
2022, Increase to Amortization	(9,362)
Thereafter, Increase to Amortization	(33,371)
Amortizable Intangible Assets, Net Carrying Amount	(107,156)	$ (121,072)
2018 (Remainder), Reduction of Rent Expense	15
2019, Reduction of Rent Expense	58
2020, Reduction of Rent Expense	58
2021, Reduction of Rent Expense	58
2022, Reduction of Rent Expense	58
Thereafter, Reduction of Rent Expense	346
Reduction of Rent Expense, Total	593
2018 (Remainder), Net Income (Expense)	(5,463)
2019, Net Income (Expense)	(15,617)
2020, Net Income (Expense)	(9,268)
2021, Net Income (Expense)	(5,520)
2022, Net Income (Expense)	(1,899)
Thereafter, Net Income (Expense)	23,295
Total, Net Income (Expense)	$ (14,472)