Summary of Significant Accounting Policies (Notes Receivable) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for Doubtful Accounts Receivable	$ 13,000,000	$ 13,500,000
Tenant receivables and accrued rent receivables, gross	3,200,000	3,100,000
Notes receivable	7,026,000	7,226,000
Investment Income, Interest	1,044,000	3,008,000	1,810,000
Purchase money mortgage loan repayments terms	12/31/2012
20 Year Amortization Period [Member] | Purchase money mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable	7,000,000	7,200,000
Interest rate	8.50%
Notes receivable amortization period, years	20 years		20 years
Due 2016 [Member] | Purchase money mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notes receivable amortization period, years	7 years		7 years
Proceeds from Collection of Notes Receivable	23,500,000
Trenton Properties [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of properties sold			2
Gross deferred gain on sale of properties		12,900,000
Investment Income, Interest	$ 1,000,000