New Issued Accounting Pronouncements (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 01, 2019 USD ($) capital_lease administrative_office center	Jun. 30, 2019 USD ($) center	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) center	Jun. 30, 2018 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Real estate taxes, net		$ 15,736	$ 17,466	$ 31,867	$ 35,105
Number of properties with ground lease agreements | center	12
Number of administrative office leases | administrative_office	4
Number of capital leases | capital_lease	1
Finance lease assets, number of units, centers | center	2	2		2
Finance lease obligations	$ 21,900	$ 21,851		$ 21,851
Operating leases, liabilities		$ 42,748		$ 42,748
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, right-of-use asset	44,200
Operating leases, liabilities	$ 42,900
Lease Arrangement, Lessor [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Real estate taxes, net			$ 1,000		$ 2,200