Operating Leases (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 year properties state lease
Property Subject to or Available for Operating Lease [Line Items]
Number of Real Estate Properties	87
Number of States in which Entity Has Properties	13
Number Of Leases	2,500
Percent of Annualized Base Rent	2.50%
Operating Leases, Future Minimum Payments Receivable [Abstract]
2012	$ 407,213
2013	369,253
2014	321,418
2015	277,155
2016	231,792
Thereafter	1,203,313
Total	$ 2,810,144
Commercial Property Lease Term Minimum	3
Commercial Property Lease Term Maximum	10
Residential Property Lease Term Maximum	1
Commercial Real Estate [Member] | Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating Lease, Term	10 years
Commercial Real Estate [Member] | Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating Lease, Term	3 years
Residential Real Estate [Member] | Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating Lease, Term	1 year