Investments in Unconsolidated Real Estate Ventures - Schedule of Investments (Details) $ in Thousands	1 Months Ended	3 Months Ended				6 Months Ended
	Jan. 31, 2019 USD ($) store	Jun. 30, 2019 USD ($) property store	Mar. 31, 2019 USD ($) store	Jun. 30, 2018 USD ($) store	Mar. 31, 2018 USD ($) store	Jun. 30, 2019 USD ($) property store	Jun. 30, 2018 USD ($) store	May 31, 2019	Jan. 01, 2019	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of Stores | store		1	14	17	5	15	22
Cash Paid		$ 8,424	$ 202,890	$ 148,648	$ 70,171	$ 211,314	$ 218,819
Number of Stores | property		239				239
Investment balance		$ 129,399				$ 129,399				$ 80,129
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		85				85
Equity Ownership %		4.00%				4.00%
Excess Profit %		4.00%				4.00%
Investment balance		$ 9,213				$ 9,213				9,334
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		36				36
Equity Ownership %		10.00%				10.00%
Excess Profit %		30.00%				30.00%
Investment balance		$ (4,774)				$ (4,774)				(4,233)
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		24				24
Equity Ownership %		34.00%				34.00%
Excess Profit %		49.00%				49.00%
Investment balance		$ (38,400)				$ (38,400)				(38,129)
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		16				16
Equity Ownership %		45.00%				45.00%
Excess Profit %		54.00%				54.00%
Investment balance		$ 17,704				$ 17,704				18,281
ESS-NYFL JV LP
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		15				15
Equity Ownership %		16.00%				16.00%		16.00%
Excess Profit %		24.00%				24.00%
Investment balance		$ 14,231				$ 14,231				0
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		10				10
Equity Ownership %		10.00%				10.00%
Excess Profit %		35.00%				35.00%
Investment balance		$ (1,903)				$ (1,903)				(1,700)
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		9				9
Equity Ownership %		10.00%				10.00%
Excess Profit %		25.00%				25.00%
Investment balance		$ 32,635				$ 32,635				26,885
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		9				9
Equity Ownership %		10.00%				10.00%
Excess Profit %		10.00%				10.00%
Investment balance		$ 8,086				$ 8,086				8,180
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		8				8
Equity Ownership %		10.00%				10.00%
Excess Profit %		28.00%				28.00%
Investment balance		$ 2,936				$ 2,936				2,331
GFN JV, LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		5				5
Equity Ownership %		10.00%				10.00%
Excess Profit %		25.00%				25.00%
Investment balance		$ 12,324				$ 12,324				10,586
Extra Space West Two LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0				0
Equity Ownership %		5.00%				5.00%
Excess Profit %		40.00%				40.00%
Investment balance		$ 0				$ 0				3,818
Extra Space West One LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		0				0
Equity Ownership %		5.00%				5.00%
Excess Profit %		40.00%				40.00%
Investment balance		$ 0				$ 0				(1,038)
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Number of Stores | property		22				22
Investment balance		$ 77,347				$ 77,347				$ 45,814
Other minority owned stores | Minimum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		10.00%				10.00%
Excess Profit %		19.00%				19.00%
Other minority owned stores | Maximum
Schedule of Equity Method Investments [Line Items]
Equity Ownership %		50.00%				50.00%
Excess Profit %		50.00%				50.00%
Extra Space West One and Two LLC
Schedule of Equity Method Investments [Line Items]
Number of Stores | store	12
Cash Paid	$ 172,505
Equity Ownership %									100.00%
Percentage interest purchased	95.00%