Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Purchase money mortgage [Member] Twenty Year Amortization Period [Member]	Dec. 31, 2012 Purchase money mortgage [Member] Twenty Year Amortization Period [Member]	Mar. 31, 2013 Purchase money mortgage [Member] Notes Receivable Due Two Thousand Sixteen [Member]	Dec. 31, 2012 Purchase money mortgage [Member] Notes Receivable Due Two Thousand Sixteen [Member]
Summary of Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Term, Minimum	1 year
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Term, Maximum	10 years
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Revenue Increased By Straight Line Rent Adjustment	$ 4,900,000	$ 6,300,000
Increase In Revenue Due To Amortization Of Deferred Rent	600,000	600,000
Decrease In Revenue Due To Lease Incentives	300,000	400,000
Guarantor Obligations, Current Carrying Value	600,000
Development costs for land	5,900,000
Increase In Shares Due To Amendments In Plan Shares Solely Available For Options And Share Appreciation Rights	3,166,998
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	5,197,094
Options Awarded Term	one to ten-year
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	500,000	400,000
Allocated Share-based Compensation Expense	2,300,000	1,700,000
Notes receivable	7,026,000		7,226,000	7,000,000	7,200,000
OneTimePaymentReceivedFromBorrowerUnderDefault [Line Items]				200,000
Notes Receivable Amortization Period, Years				20 years	20 years	7 years	7 years
Mortgage Loans on Real Estate, Interest Rate				8.50%
Interest income	$ 58,000	$ 483,000