Debt Of The Operating Partnership (Revolving Credit Facility) (Details) In Thousands, unless otherwise specified			9 Months Ended																										9 Months Ended				9 Months Ended
	Sep. 30, 2011 USD ($)	Dec. 31, 2010 USD ($)	Sep. 30, 2011 US LIBOR, EURIBOR and GBP LIBOR [Member] Revolving Credit Facility [Member]	Sep. 30, 2011 SIBOR And BBR [Member] Asia Pacific Revolving Credit Facility [Member]	Sep. 30, 2011 USD [Member] Revolving Credit Facility [Member] USD ($)	Dec. 31, 2010 USD [Member] Revolving Credit Facility [Member] USD ($)	Sep. 30, 2011 USD [Member] Asia Pacific Revolving Credit Facility [Member] USD ($)	Aug. 18, 2011 USD [Member] Asia Pacific Revolving Credit Facility [Member] USD ($)	Sep. 30, 2011 Euro [Member]	Dec. 31, 2010 Euro [Member]	Sep. 30, 2011 Euro [Member] Revolving Credit Facility [Member] EUR (€)		Sep. 30, 2011 British Sterling [Member]	Dec. 31, 2010 British Sterling [Member]	Sep. 30, 2011 British Sterling [Member] Revolving Credit Facility [Member] GBP (£)		Dec. 31, 2010 British Sterling [Member] Revolving Credit Facility [Member] GBP (£)		Sep. 30, 2011 SGD [Member]	Sep. 30, 2011 SGD [Member] Revolving Credit Facility [Member] SGD		Sep. 30, 2011 SGD [Member] Asia Pacific Revolving Credit Facility [Member] USD ($)	Sep. 30, 2011 SGD [Member] Asia Pacific Revolving Credit Facility [Member] SGD	Sep. 30, 2011 AUD [Member]	Sep. 30, 2011 AUD [Member] Revolving Credit Facility [Member] AUD		Sep. 30, 2011 AUD [Member] Asia Pacific Revolving Credit Facility [Member] USD ($)	Sep. 30, 2011 AUD [Member] Asia Pacific Revolving Credit Facility [Member] AUD	Sep. 30, 2011 Revolving Credit Facility [Member] USD ($)		Dec. 31, 2010 Revolving Credit Facility [Member] USD ($)		Sep. 30, 2011 Asia Pacific Revolving Credit Facility [Member] USD ($)
Debt of the Operating Partnership [Line Items]
Maturity Date																													Aug. 31, 2012				Aug. 17, 2012
Balance/Principal Outstanding	$ 148,800				$ 65,000	$ 312,500	$ 14,400	$ 100,000			€ 33,735	[1]			£ 50,025	[2]	£ 21,034	[2]		13,387	[3]	$ 50,000	17,500		966	[4]	$ 55,600	1,000	$ 148,760	[5]	$ 333,534	[5]	$ 14,353	[6]
Line of credit facility interest rate calculation maturity range minimum (months)			1	1
Line of credit facility interest rate calculation maturity range maximum (months)			6	6
Line of credit facility interest rate calculation margin range minimum			1.10%	1.20%
Line of credit facility interest rate calculation margin range maximum			2.00%	1.75%
Revolving credit facility rate calculation federal funds rate margin minimum			0.10%
Revolving credit facility rate calculation federal funds rate margin maximum			1.00%
Fee incurred for unused portion of credit facility minimum percentage			0.125%	0.25%
Fee incurred for unused portion of credit facility maximum percentage			0.20%	0.50%
Revolving credit facility commitments extension (years)																													1
Weighted-average interest rate					1.44%	1.40%					2.55%				1.88%		1.69%			1.42%					6.07%				1.84%		1.42%		1.73%
Exchange rate									1.34	1.34			1.56	1.56					0.76					0.97
Revolving credit facilities	$ 163,113	$ 333,534																											$ 163,113	[7]
Revolving credit facilities interest rates																													Various	[8]			Various	[8]

[1] Based on exchange rate of $1.34 to €1.00 as of September 30, 2011.

[2] Based on exchange rate of $1.56 to £1.00 as of September 30, 2011 and December 31, 2010.

[3] Based on exchange rate of $0.76 to S$1.00 as of September 30, 2011.

[4] Based on exchange rate of $0.97 to A$1.00 as of September 30, 2011.

[5] (3) Balances as of September 30, 2011 and December 31, 2010 are as follows (balances, in thousands): Denomination of Draw Balance as ofSeptember 30, 2011 Weighted-averageinterest rate Balance as ofDecember 31, 2010 Weighted-averageinterest rate US ($) $ 65,000 1.44 % $ 312,500 1.40 % Euro (€) 33,735 (a) 2.55 % — — British Sterling (£) 50,025 (b) 1.88 % 21,034 (b) 1.69 % Total $ 148,760 1.84 % $ 333,534 1.42 % (a) Based on exchange rate of $1.34 to €1.00 as of September 30, 2011. (b) Based on exchange rate of $1.56 to £1.00 as of September 30, 2011 and December 31, 2010.

[6] (4) Balances as of September 30, 2011 are as follows (balances, in thousands): Denomination of Draw Balance as ofSeptember 30, 2011 Weighted-averageinterest rate Singapore Dollar (S$) $ 13,387 (a) 1.42 % Australian Dollar (A$) 966 (b) 6.07 % Total $ 14,353 1.73 % (a) Based on exchange rate of $0.76 to S$1.00 as of September 30, 2011. (b) Based on exchange rate of $0.97 to A$1.00 as of September 30, 2011.

[7] Effective August 31, 2011, we exercised the second and final one-year extension option to our corporate revolving credit facility, which extended its maturity date from August 31, 2011 to August 31, 2012.

[8] The interest rate for borrowings under our corporate revolving credit facility equals, at our election, either (i) US LIBOR, EURIBOR and GBP LIBOR (ranging from 1- to 6-month maturities) plus a margin of between 1.10% and 2.00% or (ii) the greater of (x) the base rate announced by the lender and (y) 1/2 of 1% per annum above the federal funds rate, plus a margin of between 0.100%—1.000%. In each case, the margin is based on our total leverage ratio. We incur a fee ranging from 0.125% to 0.20% for the unused portion of our corporate revolving credit facility. The interest rate for borrowings under our Asia Pacific revolving credit facility equals, at our election, either (i) SIBOR and BBR (ranging from 1- to 6-month maturities) plus a margin of between 1.20% and 1.75%. We incur a fee ranging from 0.25% to 0.50% for the unused portion of our Asia Pacific revolving credit facility.