Real Estate and Other Activities - Net Assets Acquired (Parenthetical) (Detail) $ in Thousands, £ in Millions		12 Months Ended
		Dec. 31, 2023 USD ($)	Dec. 31, 2022	Dec. 31, 2021 USD ($)	Dec. 31, 2023 GBP (£)	Jun. 30, 2021 Property	Mar. 31, 2021 GBP (£)
Business Acquisition [Line Items]
Weighted-average useful life of acquired intangible lease assets (in years)		24 years
Advanced to the mortgage loan | $	[1]	$ 22,900		$ 1,103,410
Priory Group [Member]
Business Acquisition [Line Items]
Number of real estate assets acquired | Property						35
Mortgage Loans [Member] | Priory Group [Member]
Business Acquisition [Line Items]
Advanced to the mortgage loan | £					£ 23		£ 800
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	21 years 3 months 18 days	34 years 6 months

[1] The 2023 column includes a $23 million mortgage loan that was converted to fee simple ownership of one property as described under the Lifepoint Transaction below. The 2021 column includes an £800 million mortgage loan advanced to the Priory Group (“Priory”) in the first quarter of 2021 and converted to fee simple ownership of 35 properties in the second quarter of 2021 as described below.