Intangibles (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Intangible assets:
Above market lease intangibles	$ 215,367,000	$ 210,358,000
In-place and other lease intangibles	766,337,000	590,500,000
Other intangibles	33,378,000	16,169,000
Accumulated amortization	(352,692,000)	(188,442,000)
Goodwill	490,452,000	448,393,000
Net intangible assets	1,152,842,000	1,076,978,000
Remaining weighted average amortization period of above market lease intangible assets (in years)	9 years 6 months	10 years 1 month 6 days
Remaining weighted average amortization period of in-place lease intangible assets (in years)	23 years 3 months 18 days	22 years 4 months 24 days
Remaining weighted average amortization period of other intangible assets (in years)	8 years 7 months 6 days	13 years 6 months
Remaining weighted average amortization period of lease-related intangible assets (in years)	19 years 3 months 18 days	18 years 6 months
Intangible liabilities:
Below market lease intangibles	429,907,000	442,612,000
Other lease intangibles	28,966,000	27,157,000
Accumulated amortization	(78,560,000)	(37,607,000)
Purchase option intangibles	36,048,000	112,670,000
Net intangible liabilities	416,361,000	544,832,000
Remaining weighted average amortization period of below market lease intangible liabilities (in years)	15 years 3 months 18 days	15 years 3 months 18 days
Remaining weighted average amortization period of other lease intangible liabilities (in years)	15 years 9 months 18 days	7 years 10 months 24 days
Remaining weighted average amortization period of lease-related intangible liabilities (in years)	15 years 3 months 18 days	15 years 2 months 12 days
Intangibles
Net amortization expense	123,300,000	62,500,000	6,900,000
Estimated net amortization of the intangibles during 2012	63,000,000
Estimated net amortization of the intangibles during 2013	43,100,000
Estimated net amortization of the intangibles during 2014	31,600,000
Estimated net amortization of the intangibles during 2015	23,800,000
Estimated net amortization of the intangibles during 2016	$ 14,800,000