Schedule III - Real Estate and Accumulated Depreciation and Amortization - Schedule of Changes in Real Estate Assets and Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment in real estate:
Balance at beginning of year	$ 1,043,106	$ 970,964	$ 782,166
Acquisitions and capital expenditures	80,518	84,069	205,598
Impairments	(4,252)	(7,950)	(10,623)
Sales and condemnations	(2,246)	(3,091)	(4,520)
Lease expirations/settlements	(3,475)	(886)	(1,657)
Balance at end of year	1,113,651	1,043,106	970,964
Accumulated depreciation and amortization:
Balance at beginning of year	150,691	133,353	120,576
Depreciation and amortization	21,573	20,549	17,018
Impairments	(240)	(1,780)	(1,301)
Sales and condemnations	(546)	(530)	(1,229)
Lease expirations/settlements	(5,586)	(901)	(1,711)
Balance at end of year	$ 165,892	$ 150,691	$ 133,353