CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 361,775	$ 363,261	$ 249,729
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization (including amounts in discontinued operations)	764,775	459,704	206,064
Amortization of deferred revenue and lease intangibles, net	(17,118)	(12,159)	(1,764)
Other non-cash amortization	(39,943)	(13,163)	8,750
Change in fair value of financial instruments	99	2,959	0
Stock-based compensation	20,784	19,346	14,078
Straight-lining of rental income, net	(24,042)	(14,885)	(10,167)
Loss on extinguishment of debt, net	37,640	27,604	9,791
Gain on real estate dispositions, net (including amounts in discontinued operations)	(80,952)	0	(25,241)
Gain on real estate loan investments	(5,230)	(3,255)	(915)
Gain on sale of marketable securities	0	(733)	0
Income tax (benefit) expense (including amounts in discontinued operations)	(6,286)	(31,137)	5,201
(Income) loss from unconsolidated entities	(1,509)	52	664
Gain on re-measurement of equity interest upon acquisition, net	(16,645)	0	0
Other	10,315	4,446	(46)
Changes in operating assets and liabilities:
Decrease (increase) in other assets	3,756	424	(8,245)
Increase (decrease) in accrued interest	9,969	(9,150)	1,311
Decrease in accounts payable and other liabilities	(24,572)	(20,117)	(1,588)
Net cash provided by operating activities	992,816	773,197	447,622
Cash flows from investing activities:
Net investment in real estate property	(1,453,065)	(531,605)	(274,441)
Purchase of private investment funds	(276,419)	0	0
Purchase of noncontrolling interest	(3,934)	(3,319)	(42,333)
Investment in loans receivable	(452,558)	(628,133)	(38,725)
Funds held in escrow for future development expenditures	(28,050)	0	0
Proceeds from real estate disposals	149,045	20,618	58,163
Proceeds from loans receivable	43,219	220,179	19,291
Proceeds from sale or maturity of marketable securities	37,500	23,050	0
Development project expenditures	(114,002)	(47,591)	(1,662)
Capital expenditures	(69,430)	(50,473)	(18,193)
Other	(1,995)	(165)	(4,020)
Net cash used in investing activities	(2,169,689)	(997,439)	(301,920)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	84,938	537,452	28,564
Proceeds from debt	2,710,405	1,343,640	597,382
Repayment of debt	(1,193,023)	(1,388,962)	(524,760)
Payment of deferred financing costs	(23,770)	(20,040)	(2,694)
Issuance of common stock, net	342,469	299,847	0
Cash distribution to common stockholders	(728,546)	(521,046)	(336,085)
Cash distribution to redeemable OP unitholders	(4,446)	(2,359)	0
Purchases of redeemable OP units	(4,601)	(185)	0
Distributions to noncontrolling interest	(5,215)	(2,556)	(8,082)
Other	20,703	2,491	14,223
Net cash provided by (used in) financing activities	1,198,914	248,282	(231,452)
Net increase (decrease) in cash and cash equivalents	22,041	24,040	(85,750)
Effect of foreign currency translation on cash and cash equivalents	60	(45)	165
Cash and cash equivalents at beginning of period	45,807	21,812	107,397
Cash and cash equivalents at end of period	67,908	45,807	21,812
Supplemental disclosure of cash flow information:
Interest paid including swap payments and receipts	329,655	257,175	161,352
Assets and liabilities assumed from acquisitions:
Real estate investments	582,694	10,973,093	125,846
Utilization of funds held for an Internal Revenue Code Section 1031 exchange	(134,003)	0	0
Other assets acquired	77,730	594,176	(385)
Debt assumed	412,825	3,651,089	125,320
Other liabilities	70,391	952,279	141
Deferred income tax liability	4,299	43,889	0
Redeemable OP unitholder interests	0	100,888	0
Noncontrolling interests	34,580	81,192	0
Equity issued	4,326	6,737,932	0
Debt transferred on the sale of assets	$ 14,535	$ 0	$ 0