Intangible Assets and Liabilities - Summary of Future Amortization Expense (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Amortization Income
2018	$ 7,956
2019	7,193
2020	6,328
2021	5,359
2022	5,666
Thereafter	21,030
Intangible liabilities, net	53,532	$ 43,939
Acquired-in-Place Lease Intangibles [Member]
Amortization Expense
2018	20,419
2019	17,496
2020	14,244
2021	11,032
2022	8,294
Thereafter	31,987
Total future amortization expense	103,472
Acquired Above Market Lease Costs [Member]
Amortization Expense
2018	2,822
2019	2,077
2020	1,683
2021	1,263
2022	833
Thereafter	3,261
Total future amortization expense	11,939
Deferred Leasing Costs [Member]
Amortization Expense
2018	2,266
2019	1,504
2020	1,327
2021	1,090
2022	797
Thereafter	1,729
Total future amortization expense	$ 8,713