Fair Value of Financial Instruments - Summary of Fair Value Information of Financial Instruments (Parenthetical) (Detail) - Fair Value, Recurring [Member] $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021 Health_Center	Dec. 31, 2020 Health_Center	May 31, 2020 USD ($)
Colombia [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Number of facilities acquired | Health_Center		3
Acquisition Loans [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair value | $			$ 205
Book value | $			$ 205
Acquisition Loans [Member] | Colombia [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Number of facilities acquired | Health_Center	3