Debt (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Debt Disclosure [Abstract]
Unsecured Line Of Credit Facility Maximum Borrowing Capacity	$ 250
Unsecured Line Of Credit Annual Interest Rate First Option	75 to 120 basis points
Unsecured Line Of Credit Annual Interest Rate Second Option	50 basis points
Unsecured Line Of Credit Annual Fee Range On Unused Portion	12.5 and 20 basis points
Unsecured Line Of Credit Current Interest Rate Paid	LIBOR, or 19% plus 90 basis points
Unsecured Line Of Credit Unused Portion Basis Points	15 basis points
Line Of Credit Facility Remaining Borrowing Capacity	233.2
Increase in unsecured line of credit	91.4
Secured Line Of Credit Facility Maximum Borrowing Capacity	30
Secured Line Of Credit Annual Interest Rate First Option	2.50%
Secured Line Of Credit Annual Interest Rate Second Option	3.50%
Line Of Credit Facility Commitment Fee Percentage	0.25%
Line Of Credit Facility Commitment Fee Dollar	0.1
Line Of Credit Facility Unused Capacity Commitment Fee Percentage	0.50%
Carrying Value Of Properties Used To Collaterize Properties	51.2
Carrying Value of Mortgages Used To Collaterize Nonrecourse Debt	449.4
Mortgage Notes Payable Fixed Interest Rate Minimum	3.10%
Mortgage Notes Payable Fixed Interest Rate Maximum	7.80%
Mortgage Notes Payable Variable Interest Rate Minimum	1.10%
Mortgage Notes Payable Variable Interest Rate Maximum	7.30%
Maturity Dates Of Nonrecourse Debt	from 2011 to 2021
Fair Market Value Adjustment For Acquired Properties	1.1
Acquired Mortgages Weighted Average Rate	5.80%
Acquired Mortgages Remaining Term	8.3 years
Nonrecourse Mortgage Fair Value	87.6
Nonrecourse Debt Carrying Value	88.7
Long Term Debt By Maturity [Abstract]
2011 (remainder)	21,565
2012	270,514
2013	8,544
2014	12,303
2015	48,824
Thereafter through 2021	215,491
Total Scheduled Debt Principal Payments	$ 577,241