Equity - Noncontrolling Interest (Details)	12 Months Ended
Dec. 31, 2017 USD ($) item	Mar. 31, 2018 USD ($)
Noncontrolling interest
Investment Commitment		$ 205,608,000
87-unit ALF and MC \| 2017 Acquisitions \| ALF and MC
Noncontrolling interest
Number of beds/units acquired \| item	87
Purchase Price	$ 10,000,000
Economic interest held (as a percent)	90.00%
110-unit ILF/ALF/MC \| Wisconsin \| 2017 Acquisitions \| ALF/ILF/MC
Noncontrolling interest
Investment Commitment	$ 22,471,000
Number of beds/units under development \| item	110
Economic interest held (as a percent)	90.00%

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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Balance Type:	credit
Period Type:	duration