Intangible Assets (Intangibles - Future Amortization) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Future Amortization of Intangible Assets:
Weighted average remaining lease term	14 years
2018	$ 26,790
2019	20,505
2020	15,816
2021	11,542
2022	7,850
Thereafter	31,575
Finite-lived intangibles, net	114,078
Below Market Rents
Future Amortization of Intangible Liabilities:
2018	(13,464)
2019	(11,914)
2020	(10,817)
2021	(9,036)
2022	(6,402)
Thereafter	(17,056)
Finite-lived intangible liabilities, net	$ (68,689)
Weighted average remaining lease term	4 years
Above Market Ground Lease
Future Amortization of Intangible Liabilities:
2018	$ (46)
2019	(46)
2020	(46)
2021	(46)
2022	(46)
Thereafter	(1,535)
Finite-lived intangible liabilities, net	$ (1,765)
Weighted average remaining lease term	38 years
Below Market Ground Lease
Future Amortization of Intangible Assets:
2018	$ 481
2019	464
2020	449
2021	435
2022	421
Thereafter	15,817
Finite-lived intangible assets, net	$ 18,067	$ 18,344
Weighted average remaining lease term	66 years
Above Market Rents
Future Amortization of Intangible Assets:
2018	$ 6,364
2019	5,438
2020	4,537
2021	3,444
2022	2,348
Thereafter	4,786
Finite-lived intangible assets, net	$ 26,917	40,260
Weighted average remaining lease term	4 years
In Place Leases
Future Amortization of Intangible Assets:
2018	$ 33,455
2019	26,563
2020	21,693
2021	16,745
2022	11,529
Thereafter	29,563
Finite-lived intangible assets, net	$ 139,548	$ 185,251
Weighted average remaining lease term	5 years