Segment Information - Schedule of Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Revenues:	$ 511,386	$ 474,988	$ 1,014,436	$ 918,550
Operating expenses:	238,047	213,572	477,555	421,824
Net operating income:	273,339	275,665	536,881	510,975
Management fees and other income	22,206	20,517	43,590	40,474
Transaction related costs	0	(1,465)	0	(1,465)
General and administrative expense	(34,842)	(31,251)	(69,605)	(61,013)
Depreciation and amortization expense	(79,086)	(69,067)	(157,576)	(136,973)
Gain on real estate transactions	0	14,249	0	14,249
Interest expense	(86,372)	(47,466)	(166,471)	(90,004)
Interest income	21,077	15,060	40,515	34,049
Equity in earnings and dividend income from unconsolidated real estate entities	13,254	10,190	23,559	19,287
Income tax expense	(5,986)	(5,615)	(10,294)	(8,756)
Net income	215,312	247,834	424,190	465,551
Operating Segments
Segment Reporting Information [Line Items]
Revenues:	489,180	454,471	970,846	878,076
Operating expenses:	124,119	111,789	250,374	222,373
Net operating income:	365,061	342,682	720,472	655,703
Self-Storage Operations | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	440,747	408,044	874,709	787,852
Operating expenses:	114,637	104,252	231,803	207,794
Net operating income:	326,110	303,792	642,906	580,058
Tenant Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Revenues:	48,433	46,427	96,137	90,224
Operating expenses:	9,482	7,537	18,571	14,579
Net operating income:	$ 38,951	$ 38,890	$ 77,566	$ 75,645