Real Property Acquisitions and Development - Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Business Acquisition [Line Items]
Land and land improvements	$ 86,220	$ 56,605
Buildings and improvements	588,738	304,702
Acquired lease intangibles	16,953	34,633
Receivables and other assets	642	396
Total assets acquired	692,553	396,336
Accrued expenses and other liabilities	(11,892)	(2,707)
Total liabilities acquired	(11,892)	(2,707)
Noncontrolling interests	(19,376)	(2,827)
Cash disbursed for acquisitions	661,285	390,802
Construction in progress additions	153,383	106,644
Less: Capitalized interest	(9,358)	(9,287)
Accruals	319	(4,326)
Cash disbursed for construction in progress	144,344	93,031
Capital improvements to existing properties	94,483	122,103
Total cash invested in real property, net of cash acquired	900,112	605,936
Cash acquired from acquisition	301	580
Seniors Housing Operating
Business Acquisition [Line Items]
Land and land improvements	25,636	15,758
Buildings and improvements	167,791	132,480
Acquired lease intangibles	10,679	10,810
Receivables and other assets	634	257
Total assets acquired	204,740	159,305
Accrued expenses and other liabilities	(2,923)	(671)
Total liabilities acquired	(2,923)	(671)
Noncontrolling interests	(2,597)	(2,827)
Cash disbursed for acquisitions	199,220	155,807
Construction in progress additions	93,108	53,705
Less: Capitalized interest	(6,014)	(5,470)
Accruals	8	(1,343)
Cash disbursed for construction in progress	87,102	46,892
Capital improvements to existing properties	64,438	87,002
Total cash invested in real property, net of cash acquired	350,760	289,701
Triple-net
Business Acquisition [Line Items]
Land and land improvements	30,849	0
Buildings and improvements	268,210	765
Acquired lease intangibles	0	0
Receivables and other assets	0	0
Total assets acquired	299,059	765
Accrued expenses and other liabilities	(8,703)	0
Total liabilities acquired	(8,703)	0
Noncontrolling interests	(2,056)	0
Cash disbursed for acquisitions	288,300	765
Construction in progress additions	46,904	26,262
Less: Capitalized interest	(1,238)	(1,826)
Accruals	0	0
Cash disbursed for construction in progress	45,666	24,436
Capital improvements to existing properties	15,568	4,700
Total cash invested in real property, net of cash acquired	349,534	29,901
Outpatient Medical
Business Acquisition [Line Items]
Land and land improvements	29,735	40,847
Buildings and improvements	152,737	171,457
Acquired lease intangibles	6,274	23,823
Receivables and other assets	8	139
Total assets acquired	188,754	236,266
Accrued expenses and other liabilities	(266)	(2,036)
Total liabilities acquired	(266)	(2,036)
Noncontrolling interests	(14,723)	0
Cash disbursed for acquisitions	173,765	234,230
Construction in progress additions	13,371	26,677
Less: Capitalized interest	(2,106)	(1,991)
Accruals	311	(2,983)
Cash disbursed for construction in progress	11,576	21,703
Capital improvements to existing properties	14,477	30,401
Total cash invested in real property, net of cash acquired	$ 199,818	$ 286,334