Real Estate and Lending Activities - Alecto Facilities - Additional Information (Detail) - Alecto Healthcare Services [Member]	3 Months Ended
Mar. 31, 2019 Property
Business Acquisition [Line Items]
Number of leased properties	4
Total Gross Assets [Member] \| Customer Concentration Risk [Member]
Business Acquisition [Line Items]
Percentage of Total Gross Assets	1.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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