Real Estate and Accumulated Depreciation - Changes in Total Real Estate Investments and Related Accumulated Depreciation (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total real estate investments:
Balance, beginning of year	$ 2,124,796	$ 2,081,597	$ 1,948,165
Acquisitions	108,279	0	0
Improvements	54,177	45,396	135,966
Retirements	(3,126)	(2,197)	(2,534)
Balance, end of year	2,284,126	2,124,796	2,081,597
Total accumulated depreciation:
Balance, beginning of year	607,706	563,474	525,518
Depreciation expense	45,487	45,865	40,490
Retirements	(3,080)	(1,633)	(2,534)
Balance, end of year	$ 650,113	$ 607,706	$ 563,474