Schedule IV - Schedule of Mortgage Loan on Real Estate (Parenthetical) (Detail) (USD $)	Dec. 31, 2014
Mortgage Loans on Real Estate [Line Items]
Carrying amount of mortgages, federal income tax purposes	$ 397,500,000
Unamortized loan issue costs	$ 100,000
Long-Term First Mortgage Loan [Member] \| Ernest Mortgage Loan [Member]
Mortgage Loans on Real Estate [Line Items]
Number of properties	4

Amount of the federal income tax basis of mortgage loans on real estate.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule IV)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29.8)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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