Segment Information (Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Total assets	$ 24,692,208	$ 22,584,555
Percentage of total assets	100.00%	100.00%
Operating Segments \| Triple Net Leased Properties
Assets
Total assets	$ 6,381,657	$ 6,795,142
Percentage of total assets	25.80%	30.10%
Operating Segments \| Senior Living Operations
Assets
Total assets	$ 10,142,023	$ 8,156,187
Percentage of total assets	41.10%	36.10%
Operating Segments \| Office Operations
Assets
Total assets	$ 7,173,401	$ 6,772,957
Percentage of total assets	29.10%	30.00%
All Other
Assets
Total assets	$ 995,127	$ 860,269
Percentage of total assets	4.00%	3.80%

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant