Limited Liability Companies Accounted for Under Equity Method (Parenthetical) (Detail) $ in Millions	Dec. 31, 2017 USD ($)
Brunswick Associates
Schedule Of Equity Method Investments [Line Items]
Third-party term loan	$ 8.4
Grayson Properties
Schedule Of Equity Method Investments [Line Items]
Third-party term loan	14.2
FTX MOB Phase II limited partnership
Schedule Of Equity Method Investments [Line Items]
Third-party term loan	5.2
Committed investment in equity and debt financing, funded	2.5
Commitment to investment	$ 2.1