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, 2019	Mar. 31, 2018
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	$ 43,562	$ 44,253
Buildings and improvements	232,546	415,470
Acquired lease intangibles	15,147	54,657
Right of use assets, net	2,012
Receivables and other assets	264	266
Total assets acquired	293,531	514,646
Secured debt	(43,209)	(89,973)
Lease liabilities	(961)
Accrued expenses and other liabilities	(2,800)	(13,446)
Total liabilities acquired	(46,970)	(103,419)
Noncontrolling interests	(8,951)	(5,618)
Cash disbursed for acquisitions	237,610	405,609
Construction in progress additions	59,106	29,215
Less: Capitalized interest	(2,327)	(2,336)
Foreign currency translation	(1,433)	(5,032)
Accruals	45	888
Cash disbursed for construction in progress	55,391	22,735
Capital improvements to existing properties	56,935	46,547
Total cash invested in real property, net of cash acquired	349,936	474,891
Cash acquired from acquisition	517	4,105
Seniors Housing Operating
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	6,831	35,193
Buildings and improvements	97,759	372,562
Acquired lease intangibles	4,945	48,805
Right of use assets, net	0
Receivables and other assets	264	265
Total assets acquired	109,799	456,825
Secured debt	(43,209)	(89,973)
Lease liabilities	0
Accrued expenses and other liabilities	(848)	(12,808)
Total liabilities acquired	(44,057)	(102,781)
Noncontrolling interests	(7,895)	(5,618)
Cash disbursed for acquisitions	57,847	348,426
Construction in progress additions	37,088	10,562
Less: Capitalized interest	(1,136)	(891)
Foreign currency translation	(1,332)	(5,032)
Accruals	0	0
Cash disbursed for construction in progress	34,620	4,639
Capital improvements to existing properties	43,300	31,325
Total cash invested in real property, net of cash acquired	135,767	384,390
Triple-net
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	7,427	1,691
Buildings and improvements	74,116	235
Acquired lease intangibles	0	0
Right of use assets, net	0
Receivables and other assets	0	0
Total assets acquired	81,543	1,926
Secured debt	0	0
Lease liabilities	0
Accrued expenses and other liabilities	0	(6)
Total liabilities acquired	0	(6)
Noncontrolling interests	(1,056)	0
Cash disbursed for acquisitions	80,487	1,920
Construction in progress additions	7,543	15,850
Less: Capitalized interest	(390)	(847)
Foreign currency translation	(101)	0
Accruals	0	0
Cash disbursed for construction in progress	7,052	15,003
Capital improvements to existing properties	3,768	2,351
Total cash invested in real property, net of cash acquired	91,307	19,274
Outpatient Medical
Estimated Fair Value of Allocated Purchase Price of Asset and Liabilities
Land and land improvements	29,304	7,369
Buildings and improvements	60,671	42,673
Acquired lease intangibles	10,202	5,852
Right of use assets, net	2,012
Receivables and other assets	0	1
Total assets acquired	102,189	55,895
Secured debt	0	0
Lease liabilities	(961)
Accrued expenses and other liabilities	(1,952)	(632)
Total liabilities acquired	(2,913)	(632)
Noncontrolling interests	0	0
Cash disbursed for acquisitions	99,276	55,263
Construction in progress additions	14,475	2,803
Less: Capitalized interest	(801)	(598)
Foreign currency translation	0	0
Accruals	45	888
Cash disbursed for construction in progress	13,719	3,093
Capital improvements to existing properties	9,867	12,871
Total cash invested in real property, net of cash acquired	$ 122,862	$ 71,227