Real Estate and Other Activities - Investments in Unconsolidated Operating Entities - Additional Information (Detail) SFr in Millions, $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 CHF (SFr)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
PHP Holdings Equity Investment [Member]
Business Acquisition [Line Items]
Favorable fair market value adjustment on investment	$ 30.0
Swiss Medical Network [Member]
Business Acquisition [Line Items]
Favorable fair market value adjustment on investment | SFr		SFr 20
Other [Member] | COVID-19 Pandemic [Member]
Business Acquisition [Line Items]
Favorable non-cash fair value adjustment on investment				$ 12.6
Unfavorable non-cash fair value adjustment on investment			$ 48.7