Goodwill and Other Intangibles (Intangible Lease Assets and Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Intangible lease liabilities, accumulated amortization	$ 42,629	$ 38,340
Below-market lease, Weighted-Average Useful Life	17 years 4 months 24 days
Intangible lease liabilities, net	$ 245,093	251,692
Total Intangible Lease Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, net	1,686,900	1,771,532
In-Place Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	$ 405,753	398,770
Intangible lease assets, Weighted-Average Useful Life	13 years 6 months
Intangible lease assets, net	$ 1,381,547	1,458,354
Leasing Commissions [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	$ 1,137	1,035
Intangible lease assets, Weighted-Average Useful Life	9 years 2 months 12 days
Intangible lease assets, net	$ 6,060	4,872
Above-Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible lease assets, accumulated amortization	$ 51,944	47,041
Intangible lease assets, Weighted-Average Useful Life	16 years 1 month 6 days
Intangible lease assets, net	$ 299,293	$ 308,306