Real Estate and Other Activities - Net Assets Acquired (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Advanced to the mortgage loan	[1]	$ 22,900
Mortgage Loans [Member] | Springstone Health Opco, LLC [Member]
Business Acquisition [Line Items]
Advanced to the mortgage loan				$ 23,000
Intangible Lease Assets [Member]
Business Acquisition [Line Items]
Weighted-average useful life of acquired intangible lease assets (in years)		24 years 9 months 18 days	20 years 4 months 24 days

[1] The 2023 column includes a $23 million mortgage loan that was converted to fee simple ownership of one property as described under Lifepoint Transaction below.