Noncontrolling Interests In Operating Partnership - Additional Information (Details) $ / shares in Units, $ in Thousands							1 Months Ended	6 Months Ended	12 Months Ended
	Nov. 02, 2016 USD ($) property shares	May 31, 2016 USD ($) shares	Nov. 13, 2015 USD ($) shares	Oct. 01, 2015 USD ($) shares	Jun. 18, 2015 USD ($) Property shares	Apr. 15, 2015 USD ($) Property shares	Nov. 30, 2016 USD ($) shares	Jun. 30, 2016 USD ($) property shares	Dec. 31, 2016 USD ($) property $ / shares shares	Dec. 31, 2015 USD ($) property shares	Dec. 31, 2014 shares
Noncontrolling Interest [Line Items]
Period used as a denomination to determine the average closing price of common stock									10 days
Ten day average closing stock price | $ / shares									$ 74.87
Consideration to be paid on redemption of common OP units									$ 419,874
Number of stores | property									99	171
Number of OP Units Issued | shares									2,779,050	2,043,613,000
Total purchase price attributable to the Company									$ 74,235	$ 142,399
Operating Partnership [Member]
Noncontrolling Interest [Line Items]
Ownership interest held by entity (as a percent)		50.00%							91.20%
Voting interests of third-party owners									8.80%
OP units outstanding | shares									5,608,038
Consideration to be paid on redemption of common OP units							$ 506
Number of units redeemed during the period | shares		2,230					6,760		23,850	787,850	18,859
Total purchase price attributable to the Company		$ 205
Maryland Property Nov 2, 2016 [Member]
Noncontrolling Interest [Line Items]
Number of stores | property	1
Number of OP Units Issued | shares	77,575,000
Total purchase price attributable to the Company	$ 5,842
Georgia Property Jun 30, 2016 [Member]
Noncontrolling Interest [Line Items]
Number of stores | property								1
Number of OP Units Issued | shares								13,764
Total purchase price attributable to the Company								$ 1,200
Texas One Property November Thirteen Two Thousand And Fifteen [Member]
Noncontrolling Interest [Line Items]
Number of stores | property								1
Number of OP Units Issued | shares			91,434
Fair value of OP Units issued to certain SmartStop unit holders			$ 7,221
Florida Property Jun 18, 2015 [Member]
Noncontrolling Interest [Line Items]
Number of stores					1					1,000
Number of OP Units Issued | shares					71,054					71,054,000
Total purchase price attributable to the Company					$ 4,773					$ 4,773
Arizona, Texas Property Apr 15, 2015 [Member]
Noncontrolling Interest [Line Items]
Number of stores						22				22,000
Number of OP Units Issued | shares						1,504,277				1,504,277,000
Total purchase price attributable to the Company						$ 101,749				$ 101,749
SmartStop Self Storage, Inc (SmartStop) [Member]
Noncontrolling Interest [Line Items]
Fair value of OP Units issued to certain SmartStop unit holders				$ 28,656
Total purchase price attributable to the Company				$ 1,300,912
SmartStop Self Storage, Inc (SmartStop) [Member] | OP Units [Member]
Noncontrolling Interest [Line Items]
Number of OP Units Issued | shares				376,848
Fair value of OP Units issued to certain SmartStop unit holders				$ 28,656