Summary of Significant Accounting Policies (Details Textuals 1) (USD $) In Millions, except Share data	1 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2009	Dec. 31, 2008	Jun. 02, 2010
Summary of Significant Accounting Policies (Textuals) [Abstract]
Leasing cost reclassified to capital expenditure						$ 14.0
Prior period depreciation and Amortization adjustment		4.7
Development expense for land	7.7	7.7			7.7
Revenue increased by straight-line rent adjustment		4.1		1.8	8.3	3.8
Increased revenue due to amortization of deferred rent		0.6		0.7	1.2	1.6
Decrease in revenue due to amortization of lease incentives		0.4		0.3	0.6	1.0
Increase in Common shares available for future awards									6,000,000
Increase in shares due to amendments in plan, shares solely available for options and share appreciation rights									3,600,000
Common shares available for future awards	5,787,730	5,787,730			5,787,730
Common shares available for options and stock appreciation rights	4,550,724	4,550,724			4,550,724
Options awarded, term	one to ten-year
Stock-based compensation expense		1.6		1.8	3.3	3.1
Stock-based compensation expense, capitalized		0.4		0.4	0.7	0.6
Additional income related to electricity charges			0.5
Overstatement of revenue due to under billing			0.5
Understatement of Revenue							$ 0.3	$ 0.2