Goodwill and Other Intangibles - Intangible Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Intangible lease liabilities:
Accumulated amortization	$ 61,631	$ 56,891
Weighted-Average Useful Life	18 years 1 month 13 days
Intangible lease liabilities, net	$ 217,721	224,023
Total Intangible Lease Assets [Member]
Intangible lease assets:
Intangible lease assets, net	1,416,296	1,478,884
In-Place Leases [Member]
Intangible lease assets:
Accumulated amortization	$ 525,079	494,131
Weighted-Average Useful Life	14 years 8 months 15 days
Intangible lease assets, net	$ 1,148,158	1,192,756
Leasing Commissions [Member]
Intangible lease assets:
Accumulated amortization	$ 2,158	1,836
Weighted-Average Useful Life	10 years 4 months 2 days
Intangible lease assets, net	$ 10,570	10,231
Above-Market Leases [Member]
Intangible lease assets:
Accumulated amortization	$ 74,206	69,670
Weighted-Average Useful Life	16 years 1 month 6 days
Intangible lease assets, net	$ 257,568	$ 275,897