Debt - Debt (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
15 Communities Held For Sale \| Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations \| Mortgage notes payable
Debt Instrument [Line Items]
Mortgage debt	$ 50.2	$ 30.1

Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29(Column G))
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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