Schedule IV - Changes in Mortgage Loans Excluding Unamortized Loan Issue Costs (Parenthetical) (Detail) $ in Thousands, £ in Millions		Dec. 31, 2021 USD ($)	Mar. 31, 2021 GBP (£)	Dec. 31, 2020 USD ($)
Mortgage Loans on Real Estate [Line Items]
Advanced to the mortgage loan	[1]	$ 1,103,410		$ 834,743
Mortgage Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Advanced to the mortgage loan				$ 835,000
Mortgage Loans [Member] | Priory Group [Member]
Mortgage Loans on Real Estate [Line Items]
Advanced to the mortgage loan | £			£ 800

[1] 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 in a portfolio of 35 properties in the second quarter of 2021 as described below. The 2020 column includes approximately $740 million of loans advanced to Steward in 2017 and exchanged for the fee simple real estate of two hospitals as described below, as well as approximately $100 million of loans advanced to Ernest Health, Inc. (“Ernest”) in 2012 and exchanged for the fee simple real estate of four hospitals as described below.