Real Estate and Lending Activities - Direct Financing Leases - Additional Information (Detail) $ in Millions		3 Months Ended
	Mar. 15, 2018 USD ($)	Mar. 31, 2019 Lease
Ernest [Member]
Direct Financing Lease Income [Line Items]
Number of direct financing leases		14
Prime Facilities [Member]
Direct Financing Lease Income [Line Items]
Number of direct financing leases		10
Alecto Healthcare Services [Member]
Direct Financing Lease Income [Line Items]
Number of direct financing leases		2
Vibra Healthcare, LLC [Member] | Acute Care Hospital [Member]
Direct Financing Lease Income [Line Items]
Term of lease	15 years
Existence of option to extend	true
Number of lease extension options		with three extension options of five years each.
Term of lease extension, years	5 years
Write off of unbilled direct finance lease rent | $	$ 1.5