Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended		3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 02, 2010	Jun. 30, 2012 PJP VII [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2011 Restricted Stock [Member]	Jun. 30, 2012 Restricted Stock [Member]	Jun. 30, 2011 Restricted Stock [Member]	Jun. 30, 2012 Banco Santander Bonds [Member]	Mar. 23, 2012 Banco Santander Bonds [Member]
Variable Interest Entity [Line Items]
Cash Received for Held-to-Maturity Securities Sold											$ 20,009,000
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount												50,000,000
Guarantor Obligations, Current Carrying Value						700,000
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Development costs for land	7,900,000		7,900,000
Revenue increased by straight-line rent adjustment	5,300,000	4,100,000	11,600,000	8,300,000
Increased revenue due to amortization of deferred rent	600,000	600,000	1,200,000	1,200,000
Decrease in revenue due to amortization of lease incentives	100,000	400,000	500,000	600,000
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	4,108,336		4,108,336		3,600,000
Common shares available for future awards	5,272,017		5,272,017
Options awarded, term			one to ten-year
Award vesting term, minimum			1 year
Award vesting term, maximum			10 years
Stock-based compensation expense	1,900,000	1,600,000	3,600,000	3,300,000			800,000	800,000	1,500,000	1,600,000
Stock-based compensation expense, capitalized	$ 500,000	$ 400,000	$ 900,000	$ 700,000			$ 200,000	$ 100,000	$ 300,000	$ 300,000
Distributable income minimum percentage			90.00%