Commitments and Contingencies (Details Textuals) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Commitments and Contingencies (Textuals) [Abstract]
Outstanding construction financings for leased properties	$ 212,161,000		$ 212,161,000
Additional financing to complete construction	219,306,000		219,306,000
Total contingent purchase obligations	80,151,000		80,151,000
Minimum part of economic life of the leased asset to be classified as capital lease	75.00%		75.00%
Minimum net present value of the future minimum lease payments to be classified as capital lease	90.00%		90.00%
Operating lease obligations relating to certain ground leases	220,688,000		220,688,000
Rental expense relating to company office space	615,000	303,000	1,130,000	635,000
Aggregate future minimum rentals to be received	30,354,000		30,354,000
Gross assets under capital lease recorded in real property	181,254,000		181,254,000
Liability and property insurance [Member]
Commitments and Contingencies (Textuals) [Abstract]
Number of outstanding letters of credit			1
Letter of credit obligation	1,000,000		1,000,000
Workers compensation insurance [Member]
Commitments and Contingencies (Textuals) [Abstract]
Number of outstanding letters of credit			2
Letter of credit obligation	4,200,000		4,200,000
Completion and Installation of Certain Public Improvements [Member]
Commitments and Contingencies (Textuals) [Abstract]
Number of outstanding letters of credit			1
Letter of credit obligation	67,932		67,932
Completion and Installation of Certain Public Improvements for the Benefit of Wisconsin [Member]
Commitments and Contingencies (Textuals) [Abstract]
Number of outstanding letters of credit			1
Letter of credit obligation	$ 215,000		$ 215,000