Leases - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($) Property State	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Property State	Jun. 30, 2019 USD ($)	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
Leases [Line Items]
Number of properties in portfolio | Property	946		946
Number of states in which our properties are located | State	35		35
Revenues from rental properties	$ 36,336	$ 33,560	$ 70,986	$ 66,847
Rental income contractually due from tenants in revenues from rental properties included in continuing operations	31,784	29,378	63,178	58,586
Revenue recognition adjustments included in revenues from rental properties in continuing operations	86	235	156	614
Real Estate Taxes and other municipal charges paid then reimbursed by tenants included in revenues and expenses	4,638	3,947	7,964	7,647
Lease origination costs	191	$ 93	191	$ 93
Net investment in direct financing leases	79,767		79,767			$ 82,366
Net Investments in direct financing lease, lease payments receivable	119,864		119,864			126,412
Net Investment in direct financing lease, unguaranteed estimated residual value	13,928		13,928			13,928
Net Investment in direct financing lease, deferred income	53,447		53,447			57,974
Net Investment in direct financing lease, allowance for credit losses	578		578
Operating lease liabilities	18,614		18,614			21,844
Operating lease right of use assets	$ 17,953		$ 17,953			$ 21,191
Accounting Standards Update 2016-13 [Member]
Leases [Line Items]
Net investment in direct financing leases					$ 82,366
Estimated credit loss reserve related to direct financing leases					$ 578
Accounting Standards Update 2016-02 [Member]
Leases [Line Items]
Operating lease liabilities							$ 26,087
Operating lease right of use assets							$ 25,561
Third Party Landlords [Member]
Leases [Line Items]
Number of properties leased | Property	59		59
Owned Properties [Member]
Leases [Line Items]
Number of properties | Property	887		887