Real Property Acquisitions and Development - Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Business Acquisition [Line Items]
Land and land improvements	$ 27,667	$ 56,605
Buildings and improvements	184,423	304,702
Acquired lease intangibles	1,778	34,633
Receivables and other assets	34	396
Total assets acquired	213,902	396,336
Accrued expenses and other liabilities	(8,739)	(2,707)
Total liabilities acquired	(8,739)	(2,707)
Noncontrolling interests	(2,056)	(2,827)
Cash disbursed for acquisitions	203,107	390,802
Construction in progress additions	77,783	57,415
Less: Capitalized interest	(4,496)	(4,746)
Accruals	318	(3,894)
Cash disbursed for construction in progress	73,605	48,775
Capital improvements to existing properties	28,780	69,382
Total cash invested in real property, net of cash acquired	305,492	508,959
Cash acquired from acquisition		580
Seniors Housing Operating
Business Acquisition [Line Items]
Land and land improvements	1,240	15,758
Buildings and improvements	3,491	132,480
Acquired lease intangibles	339	10,810
Receivables and other assets	34	257
Total assets acquired	5,104	159,305
Accrued expenses and other liabilities	0	(671)
Total liabilities acquired	0	(671)
Noncontrolling interests	0	(2,827)
Cash disbursed for acquisitions	5,104	155,807
Construction in progress additions	38,373	29,841
Less: Capitalized interest	(2,980)	(2,812)
Accruals	7	(2,600)
Cash disbursed for construction in progress	35,400	24,429
Capital improvements to existing properties	(3,159)	52,503
Total cash invested in real property, net of cash acquired	37,345	232,739
Triple-net
Business Acquisition [Line Items]
Land and land improvements	24,154	0
Buildings and improvements	170,362	765
Acquired lease intangibles	0	0
Receivables and other assets	0	0
Total assets acquired	194,516	765
Accrued expenses and other liabilities	(8,703)	0
Total liabilities acquired	(8,703)	0
Noncontrolling interests	(2,056)	0
Cash disbursed for acquisitions	183,757	765
Construction in progress additions	31,809	13,929
Less: Capitalized interest	(524)	(941)
Accruals	0	0
Cash disbursed for construction in progress	31,285	12,988
Capital improvements to existing properties	25,295	3,248
Total cash invested in real property, net of cash acquired	240,337	17,001
Outpatient Medical
Business Acquisition [Line Items]
Land and land improvements	2,273	40,847
Buildings and improvements	10,570	171,457
Acquired lease intangibles	1,439	23,823
Receivables and other assets	0	139
Total assets acquired	14,282	236,266
Accrued expenses and other liabilities	(36)	(2,036)
Total liabilities acquired	(36)	(2,036)
Noncontrolling interests	0	0
Cash disbursed for acquisitions	14,246	234,230
Construction in progress additions	7,601	13,645
Less: Capitalized interest	(992)	(993)
Accruals	311	(1,294)
Cash disbursed for construction in progress	6,920	11,358
Capital improvements to existing properties	6,644	13,631
Total cash invested in real property, net of cash acquired	$ 27,810	$ 259,219