Debt Of The Operating Partnership (Global Revolving Credit Facility) (Details) In Thousands, unless otherwise specified	3 Months Ended		3 Months Ended
	Mar. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2012 Global Revolving Credit Facility [Member] USD ($)		Dec. 31, 2011 Global Revolving Credit Facility [Member] USD ($)	Mar. 31, 2012 USD [Member] Global Revolving Credit Facility [Member] USD ($)	Dec. 31, 2011 USD [Member] Global Revolving Credit Facility [Member] USD ($)	Mar. 31, 2012 EUR [Member]	Dec. 31, 2011 EUR [Member]	Mar. 31, 2012 EUR [Member] Global Revolving Credit Facility [Member] EUR (€)		Mar. 31, 2012 GBP [Member]	Dec. 31, 2011 GBP [Member]	Mar. 31, 2012 GBP [Member] Global Revolving Credit Facility [Member] GBP (£)		Dec. 31, 2011 GBP [Member] Global Revolving Credit Facility [Member] GBP (£)		Mar. 31, 2012 SGD [Member] Global Revolving Credit Facility [Member] SGD		Dec. 31, 2011 SGD [Member] Global Revolving Credit Facility [Member] SGD		Mar. 31, 2012 AUD [Member] Global Revolving Credit Facility [Member] AUD		Dec. 31, 2011 AUD [Member] Global Revolving Credit Facility [Member] AUD		Mar. 31, 2012 HKD [Member] Global Revolving Credit Facility [Member] HKD
Debt of the Operating Partnership [Line Items]
Maturity Date			Nov. 03, 2015
Balance/Principal Outstanding			$ 678,554		$ 275,106	$ 498,000	$ 194,000			€ 65,914	[1]			£ 51,386	[1]	£ 49,892	[2]	44,923	[1]	28,151	[2]	14,484	[1]	3,063	[2]	3,847	[1]
Revolving credit facility basis spread on variable rate			125
Basis rate for unused portion of the credit facility			25
Revolving credit facility commitments extension (years)	1
Weighted-average interest rate			1.65%		1.67%	1.50%	1.54%			1.72%				1.98%		1.99%		1.56%		1.56%		5.67%		5.89%		1.55%
Exchange rate								1.33	1.30	1.33		1.60	1.55	1.60		1.55		0.80		0.77		1.03		1.02		0.13
Revolving credit facilities	$ 678,554	$ 275,106	$ 678,554	[3]
Revolving credit facilities interest rates			Various	[4]

[1] Based on exchange rates of $1.33 to €1.00, $1.60 to £1.00, $0.80 to 1.00 SGD, $1.03 to 1.00 AUD and $0.13 to 1.00 HKD, respectively, as of March 31, 2012.

[2] Based on exchange rates of $1.55 to £1.00, $0.77 to 1.00 SGD and $1.02 to 1.00 AUD, respectively, as of December 31, 2011.

[3] Subject to a one-year extension option exercisable by us. The bank group is obligated to grant the extension option provided we give proper notice, we make certain representations and warranties and no default exists under the global revolving credit facility.

[4] The interest rate for borrowings under the global revolving credit facility equals the applicable index plus a margin which is based on the credit rating of our long-term debt and is currently 125 basis points. An annual facility fee on the unused portion of the facility, based on the credit rating of our long-term debt and currently 25 basis points, is payable quarterly.