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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Real Estate Activities - Alecto Healthcare facilities - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Property	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Real estate impairment charge	$ 18,002	$ 5,340	$ 3,063
Alecto Healthcare Services [Member]
Business Acquisition [Line Items]
Number of leased properties \| Property	4
Real estate impairment charge	$ 30,000
Alecto Healthcare Services [Member] \| Total Gross Assets [Member] \| Customer Concentration Risk
Business Acquisition [Line Items]
Percentage of Total Gross Assets	1.00%