CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income (loss)	$ 428,253	$ 60,061	$ 1,073,474
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization of real estate, in-place lease, and other intangibles	697,143	659,989	549,499
Amortization of deferred compensation	17,368	18,162	16,563
Amortization of deferred financing costs	10,157	10,863	12,612
Straight-line rents	(24,532)	(22,479)	(23,138)
Amortization of nonrefundable entrance fees and above/below market lease intangibles	(81,914)	0	0
Equity loss (income) from unconsolidated joint ventures	67,787	8,625	2,594
Distributions of earnings from unconsolidated joint ventures	12,294	20,114	22,467
Loss (gain) on sale of real estate under direct financing leases	(41,670)	0	0
Deferred income tax expense (benefit)	(14,573)	(18,253)	(18,525)
Impairments and loan loss reserves (recoveries), net	244,253	225,937	55,260
Loss on debt extinguishments	42,912	58,364	44,162
Loss (gain) on sales of real estate, net	(550,494)	(22,900)	(925,985)
Loss (gain) upon change of control, net	(159,973)	(168,023)	(9,154)
Casualty-related loss (recoveries), net	469	(3,706)	0
Other non-cash items	2,175	(2,569)	2,569
Decrease (increase) in accounts receivable and other assets, net	15,281	(49,771)	5,686
Increase (decrease) in accounts payable, accrued liabilities, and deferred revenue	93,495	71,659	40,625
Net cash provided by (used in) operating activities	758,431	846,073	848,709
Cash flows from investing activities:
Acquisitions of real estate	(1,170,651)	(1,604,285)	(426,080)
Development, redevelopment, and other major improvements of real estate	(791,566)	(626,904)	(503,643)
Leasing costs, tenant improvements, and recurring capital expenditures	(94,121)	(108,844)	(106,193)
Proceeds from sales of real estate, net	1,304,375	230,455	2,044,477
Acquisition of CCRC Portfolio	(394,177)	0	0
Contributions to unconsolidated joint ventures	(39,118)	(14,956)	(12,203)
Distributions in excess of earnings from unconsolidated joint ventures	18,555	27,072	26,472
Proceeds from insurance recovery	1,802	9,359	0
Proceeds from the RIDEA II transaction, net	0	0	335,709
Proceeds from the U.K. JV transaction, net	0	89,868	393,997
Proceeds from the Sovereign Wealth Fund Senior Housing JV transaction, net	0	354,774	0
Proceeds from sales/principal repayments on debt investments and direct financing leases	202,763	274,150	148,024
Investments in loans receivable, direct financing leases, and other	(45,562)	(79,467)	(71,281)
Net cash provided by (used in) investing activities	(1,007,700)	(1,448,778)	1,829,279
Cash flows from financing activities:
Borrowings under bank line of credit and commercial paper	4,742,600	7,607,788	1,823,000
Repayments under bank line of credit and commercial paper	(4,706,010)	(7,597,047)	(2,755,668)
Issuance and borrowings of debt, excluding bank line of credit and commercial paper	594,750	2,047,069	223,587
Repayments and repurchase of debt, excluding bank line of credit and commercial paper	(568,343)	(1,654,142)	(1,604,026)
Borrowings under term loan	0	250,000	0
Payments for debt extinguishment and deferred financing costs	(47,210)	(80,616)	(41,552)
Issuance of common stock and exercise of options	1,068,877	795,586	217,656
Repurchase of common stock	(10,529)	(5,043)	(3,432)
Dividends paid on common stock	(787,072)	(720,123)	(696,913)
Issuance of noncontrolling interests	0	33,318	299,666
Distributions to and purchase of noncontrolling interests	(40,613)	(29,519)	(82,854)
Net cash provided by (used in) financing activities	246,450	647,271	(2,620,536)
Effect of foreign exchanges on cash, cash equivalents and restricted cash	(153)	245	191
Net increase (decrease) in cash, cash equivalents and restricted cash	(2,972)	44,811	57,643
Cash, cash equivalents and restricted cash, beginning of year	184,657	139,846	82,203
Cash, cash equivalents and restricted cash, end of year	181,685	184,657	139,846
Less: cash, cash equivalents and restricted cash of discontinued operations	(70,253)	(90,874)	(78,701)
Cash, cash equivalents and restricted cash of continuing operations, end of year	$ 111,432	$ 93,783	$ 61,145