Summary of Significant Accounting Policies - Future Amortization of Deferred Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Year Ending December 31,
2019	$ 6,794
2020	27,700
2021	26,154
2022	25,856
2023	24,736
Thereafter	200,724
Total	311,964
Total	(27,332)	$ (27,218)
Deferred Financing Costs
Year Ending December 31,
2019	142
2020	561
2021	37
2022	0
2023	0
Thereafter	0
Total	740
Leasing Costs
Year Ending December 31,
2019	85
2020	405
2021	385
2022	373
2023	314
Thereafter	1,117
Total	2,679
Lease Intangibles (In-place)
Year Ending December 31,
2019	3,147
2020	12,385
2021	11,237
2022	10,371
2023	9,594
Thereafter	56,716
Total	103,450
Lease Intangibles (Above-Market)
Year Ending December 31,
2019	4,631
2020	19,114
2021	18,827
2022	18,534
2023	17,680
Thereafter	153,641
Total	232,427
Lease Intangibles (Below-Market)
Year Ending December 31,
2019	(1,211)
2020	(4,765)
2021	(4,332)
2022	(3,422)
2023	(2,852)
Thereafter	(10,750)
Total	$ (27,332)