Lease Intangibles - Scheduled Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Acquired Lease Intangibles [Abstract]
Amortizable Intangible Assets, Net Carrying Amount	$ (127,571)	$ (114,584)
In-place lease intangible assets
Acquired Lease Intangibles [Abstract]
2018, Net Increase In Lease Revenues	10,005
2019, Net Increase In Lease Revenues	9,642
2020, Net Increase In Lease Revenues	8,655
2021, Net Increase In Lease Revenues	7,503
2022, Net Increase In Lease Revenues	7,185
Thereafter, Net Increase In Lease Revenues	54,352
Net Increase In Lease Revenues, Total	97,342
2018, Increase to Amortization	(29,005)
2019, Increase to Amortization	(21,678)
2020, Increase to Amortization	(16,797)
2021, Increase to Amortization	(12,524)
2022, Increase to Amortization	(8,778)
Thereafter, Increase to Amortization	(32,290)
Amortizable Intangible Assets, Net Carrying Amount	(121,072)	$ (108,593)
2018, Reduction of Rent Expense	58
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	637
2018, Net Income (Expense)	(18,942)
2019, Net Income (Expense)	(11,978)
2020, Net Income (Expense)	(8,084)
2021, Net Income (Expense)	(4,963)
2022, Net Income (Expense)	(1,535)
Thereafter, Net Income (Expense)	22,409
Total, Net Income (Expense)	$ (23,093)