Rental Income (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Consolidated properties
Approximate future minimum rents to be received over the next five years and thereafter for non-cancelable operating leases
2014	$ 992,002
2015	939,016
2016	870,664
2017	792,471
2018	733,754
Thereafter	3,785,428
Total minimum lease payments	8,113,335
Unconsolidated properties
Approximate future minimum rents to be received over the next five years and thereafter for non-cancelable operating leases
2014	245,879
2015	195,447
2016	214,616
2017	201,671
2018	202,309
Thereafter	1,911,877
Total minimum lease payments	$ 2,971,799