Lease Intangibles - Scheduled Amortization (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Acquired Lease Intangibles [Abstract]
Amortizable Intangible Assets, Net Carrying Amount	$ (114,982)	$ (127,571)
In-place lease intangible assets
Acquired Lease Intangibles [Abstract]
2018 (Remainder), Net Increase In Lease Revenues	3,114
2019, Net Increase In Lease Revenues	9,633
2020, Net Increase In Lease Revenues	8,853
2021, Net Increase In Lease Revenues	7,670
2022, Net Increase In Lease Revenues	7,373
Thereafter, Net Increase In Lease Revenues	57,118
Net Increase In Lease Revenues, Total	93,761
2018 (Remainder), Increase to Amortization	(8,035)
2019, Increase to Amortization	(23,201)
2020, Increase to Amortization	(17,244)
2021, Increase to Amortization	(12,653)
2022, Increase to Amortization	(8,863)
Thereafter, Increase to Amortization	(39,317)
Amortizable Intangible Assets, Net Carrying Amount	(109,313)	$ (121,072)
2018 (Remainder), Reduction of Rent Expense	29
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	347
Reduction of Rent Expense, Total	608
2018 (Remainder), Net Income (Expense)	(4,892)
2019, Net Income (Expense)	(13,510)
2020, Net Income (Expense)	(8,333)
2021, Net Income (Expense)	(4,925)
2022, Net Income (Expense)	(1,432)
Thereafter, Net Income (Expense)	18,148
Total, Net Income (Expense)	$ (14,944)