Segment Information - Schedule of Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Revenues:	$ 503,050	$ 443,562
Operating expenses:	239,508	208,252
Net operating income:	263,542	235,310
Management fees and other income	21,384	19,957
General and administrative expense	(34,763)	(29,762)
Depreciation and amortization expense	(78,490)	(67,906)
Interest expense	(80,099)	(42,538)
Interest income	19,438	18,989
Equity in earnings and dividend income from unconsolidated real estate entities	10,305	9,097
Income tax expense	(4,308)	(3,141)
Net income	208,878	217,717
Operating Segments
Segment Reporting Information [Line Items]
Revenues:	481,666	423,605
Operating expenses:	126,255	110,584
Net operating income:	355,411	313,021
Self-Storage Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	433,962	379,808
Operating expenses:	117,166	103,542
Net operating income:	316,796	276,266
Tenant Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	47,704	43,797
Operating expenses:	9,089	7,042
Net operating income:	$ 38,615	$ 36,755