Segment Information (Summary Of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 717,499	$ 729,336	$ 710,950	$ 689,038	$ 692,460	$ 706,368	$ 685,528	$ 669,924	$ 2,846,823	$ 2,754,280	$ 2,668,528
Cost of operations									(752,579)	(695,731)	(657,633)
Cost of operations									(44,204)	(43,991)	(50,345)
Depreciation and amortization	(134,885)	(129,233)	(126,859)	(121,941)	(121,374)	(124,516)	(119,777)	(117,979)	(512,918)	(483,646)	(454,526)
Equity in earnings of unconsolidated real estate entities									69,547	103,495	75,655
Gain due to Shurgard public offering										151,616
General and administrative									(71,983)	(118,720)	(82,882)
Interest and other income									28,436	26,442	18,771
Interest expense									(45,641)	(32,542)	(12,690)
Foreign currency exchange gain (loss)									7,829	18,117	(50,045)
Casualty loss											(7,789)
Gain on sale of real estate									341	37,903	1,421
Net income	$ 387,097	$ 399,420	$ 371,456	$ 367,678	$ 587,906	$ 379,589	$ 405,292	$ 344,436	1,525,651	1,717,223	1,448,465
Self-Storage Operations [Member]
Segment Reporting Information [Line Items]
Revenue									2,684,552	2,597,607	2,512,433
Cost of operations									(752,579)	(695,731)	(657,633)
Net operating income									1,931,973	1,901,876	1,854,800
Depreciation and amortization									(512,918)	(483,646)	(454,526)
Net income									1,419,055	1,418,230	1,400,274
Ancillary Operations [Member]
Segment Reporting Information [Line Items]
Revenue									162,271	156,673	156,095
Cost of operations									(44,204)	(43,991)	(50,345)
Net operating income									118,067	112,682	105,750
Invesment in PSB [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated real estate entities									54,090	89,362	46,544
Investment In Shurgard [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated real estate entities									15,457	14,133	25,948
Gain due to Shurgard public offering										151,616
Net income									15,457	165,749	25,948
Allocated to Segments [Member]
Segment Reporting Information [Line Items]
Net income									1,606,669	1,786,023	1,578,516
Other Items Not Allocated To Segments [Member]
Segment Reporting Information [Line Items]
Equity in earnings of unconsolidated real estate entities											3,163
General and administrative									(71,983)	(118,720)	(82,882)
Interest and other income									28,436	26,442	18,771
Interest expense									(45,641)	(32,542)	(12,690)
Foreign currency exchange gain (loss)									7,829	18,117	(50,045)
Casualty loss											(7,789)
Gain on sale of real estate									$ 341	$ 37,903	$ 1,421