CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Cash flows from operating activities:
Net income (loss)	$ 639,926	$ (546,418)	$ 936,591
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization of real estate, in-place lease and other intangibles continuing operations	568,108	504,905	455,016
Depreciation and amortization of real estate, in-place lease and other intangibles discontinued operations	4,890	5,880	4,979
Amortization of market lease intangibles, net	(1,197)	(1,295)	(949)
Amortization of deferred compensation	22,884	26,127	21,885
Amortization of deferred financing costs	20,014	20,222	19,260
Straight-line rents	(18,003)	(28,859)	(41,032)
Loan and direct financing lease non-cash interest	599	(5,648)	1,063
Loan and direct financing lease non-cash interest discontinued operations		(90,065)	(79,349)
Deferred rental revenues	(1,959)	(2,813)	(1,884)
Equity income from unconsolidated joint ventures	(11,360)	(57,313)	(49,570)
Distributions of earnings from unconsolidated joint ventures	26,492	15,111	5,045
Lease termination income, net		(1,103)	(38,001)
Gain on sales of real estate, net	(164,698)	(6,377)	(31,298)
Deferred income tax expense	47,195
Loss on debt extinguishment	46,020
Foreign exchange and other (gains) losses, net	188	(7,178)	(2,270)
Impairment, net		1,449,748	35,913
Changes in:
Accounts receivable, net	3,813	(9,569)	(8,845)
Other assets, net	(10,805)	(19,453)	(6,287)
Accounts payable and other accrued liabilities	42,024	(23,757)	28,354
Net cash provided by operating activities	1,214,131	1,222,145	1,248,621
Cash flows from investing activities:
Acquisition of RIDEA III, net		(770,325)
Acquisition of the CCRC unconsolidated joint venture interest, net			(370,186)
Acquisitions of other real estate	(467,162)	(613,252)	(503,470)
Development of real estate	(421,322)	(281,017)	(178,513)
Leasing costs and tenant and capital improvements	(91,442)	(84,282)	(71,734)
Proceeds from sales of real estate, net	647,754	58,623	104,557
Contributions to unconsolidated joint ventures	(10,186)	(69,936)	(2,935)
Distributions in excess of earnings from unconsolidated joint ventures	28,366	30,989	2,657
Purchase of securities for debt defeasance	(73,278)
Proceeds from sales of marketable securities		2,348
Principal repayments on loans receivable, direct financing leases and other	231,990	625,701	119,511
Investments in loans receivable, direct financing leases and other	(273,693)	(575,652)	(600,019)
Decrease (increase) in restricted cash	18,356	4,798	(11,747)
Net cash used in investing activities	(410,617)	(1,672,005)	(1,511,879)
Cash flows from financing activities:
Net borrowings under bank line of credit	1,108,417	98,743	845,190
Repayments under bank line of credit	(540,000)	(511,521)
Proceeds from debt related to QCP Spin-Off, net	1,691,268
Cash impact of QCP Spin-Off	(6,096)
Borrowings under term loan		333,014
Issuance of senior unsecured notes		1,936,017	1,150,000
Repayments of senior unsecured notes	(2,000,000)	(400,000)	(487,000)
Issuance of mortgage and other debt			35,445
Loss on debt extinguishment	(45,406)
Repayments of mortgage and other debt	(316,774)	(57,845)	(447,784)
Deferred financing costs	(9,450)	(19,995)	(16,550)
Issuance of common stock and exercise of options	67,650	206,471	96,592
Repurchase of common stock	(8,685)	(8,738)	(12,703)
Dividends paid on common stock	(979,542)	(1,046,638)	(1,001,559)
Issuance of noncontrolling interests	11,834	110,775	4,674
Purchase of noncontrolling interests	(1,300)	(7,049)	(5,897)
Distributions to noncontrolling interests	(26,181)	(19,147)	(15,611)
Net cash (used in) provided by financing activities	(1,054,265)	614,087	144,797
Effect of foreign exchange on cash and cash equivalents	(1,019)	(1,537)	1,715
Net (decrease) increase in cash and cash equivalents	(251,770)	162,690	(116,746)
Cash and cash equivalents, beginning of year	346,500	183,810	300,556
Cash and cash equivalents, end of year	94,730	346,500	183,810
Less: cash and cash equivalents of discontinued operations		(6,058)	(1,894)
Cash and cash equivalents of continuing operations, end of year	$ 94,730	$ 340,442	$ 181,916