Summary of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 02, 2010
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Development costs for land	$ 9,000,000		$ 9,000,000
Revenue increased by straight-line rent adjustment	4,300,000	4,900,000	16,000,000	13,200,000
Increased revenue due to amortization of deferred rent	600,000	600,000	1,800,000	1,700,000
Decrease in revenue due to amortization of lease incentives	100,000	400,000	600,000	1,000,000
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	4,030,218		4,030,218		3,600,000
Common shares available for future awards	5,290,717		5,290,717
Options awarded, term			one to ten-year
Award vesting term, minimum			1 year
Award vesting term, maximum			10 years
Stock-based compensation expense	1,800,000	1,600,000	5,500,000	4,800,000
Stock-based compensation expense, capitalized	500,000	400,000	1,400,000	1,100,000
Distributable income minimum percentage	90.00%
PJP VII [Member]
Variable Interest Entity [Line Items]
Guarantor Obligations, Current Carrying Value	600,000		600,000
Banco Santander Bonds [Member]
Variable Interest Entity [Line Items]
Principal Amount of Held-to-maturity Securities Sold	42,105,000
Summary Of Significant Accounting Policies (Textuals) [Abstract]
Held-to-maturity Securities, Sold Security, Realized Gain (Loss)	$ (75,000)