Intangible Assets and Liabilities and Goodwill (Intangible Assets) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Remaining Weighted Average Amortization Period in Years			10 years		11 years 6 months
Intangible assets:
Accumulated amortization	$ (46,690)		$ (46,690)		$ (44,511)
Goodwill	123,884		123,884		123,884
Net intangible assets	181,208		181,208		174,754
Intangible liabilities:
Below market lease intangibles	132,182		132,182		167,789
Accumulated amortization	(68,625)		(68,625)		(72,060)
Purchase option intangibles	5,546		5,546		5,546
Net intangible liabilities	71,010		$ 71,010		$ 103,182
Below market leases, remaining weighted average amortization period			11 years 6 months		15 years
Finite-lived intangible liabilities, remaining weighted average amortization period			12 years 8 months 12 days		15 years 8 months 12 days
Intangibles
Net amortization expense	400	$ 1,200	$ 1,400	$ 2,400
Estimated net amortization of the intangibles remainder of 2017	200		200
Estimated net amortization of the intangibles during 2018	600		600
Estimated net amortization of the intangibles during 2019	1,100		1,100
Estimated net amortization of the intangibles during 2020	1,600		1,600
Estimated net amortization of the intangibles during 2021	600		600
Above market ground lease intangibles
Intangible liabilities:
Above market ground lease intangibles	1,907		$ 1,907		$ 1,907
Above market ground leases, remaining weighted average amortization period			51 years 4 months 24 days		51 years 10 months 24 days
Above market lease intangibles
Finite-Lived Intangible Assets [Line Items]
Intangible assets	52,716		$ 52,716		$ 56,570
Remaining Weighted Average Amortization Period in Years			9 years 1 month 6 days		11 years 1 month 6 days
In-place lease intangibles
Finite-Lived Intangible Assets [Line Items]
Intangible assets	48,348		$ 48,348		$ 35,861
Remaining Weighted Average Amortization Period in Years			10 years 9 months 18 days		12 years 9 months 18 days
Tradename, technology and customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 2,950		$ 2,950		$ 2,950
Remaining Weighted Average Amortization Period in Years			3 years		3 years 6 months